CHAPTER XII

CRUSTACEA OF THE PAST

Since the acceptance by naturalists of the theory of Evolution as indicating the mode of origin of the various forms of life now existing, one of the chief lines of biological investigation has had for its object the reconstruction of the pedigree (or, as it is called, the "phylogeny") of the larger groups of the animal and vegetable kingdoms. In attempting to do this, there are three main sources from which evidence may be drawn. The results of Comparative Anatomy enable us to decide with more or less confidence as to the degrees of relationship between the groups of organisms, and to distinguish between the more primitive and the more specialized; the study of Embryology is, at least, an indispensable adjunct to Comparative Anatomy, even if it does not, as was once supposed, give us an actual recapitulation of ancestral history; and, finally, the study of Fossil Remains holds out the hope that we may be able to find the ancestral types themselves.

It is clear that evidence from the last-named source, when it is available, is the most important of all, since the order of succession of the various types is given by that of the rock strata in which they occur, and we can be quite certain that we are dealing, if not with the actual ancestors, at least with the forerunners of existing species. The "imperfection of the geological record," however, is so great that the organisms preserved in the fossil state represent only an insignificant part of the whole number of organisms that have lived on the globe since life began; and it is not surprising, therefore, that in many groups the study of fossils has hitherto afforded little help towards the working out of their genealogical history. Thus, among Crustacea there are many important groups such as the Copepoda, which are entirely unknown as fossils, their small and delicate bodies being ill adapted for preservation, although there is every reason to suppose that they are a very primitive and very ancient group. In many fossil Crustacea only the hard shell or carapace has been preserved, the appendages being lost or represented only by indecipherable fragments, and in some cases it is hardly possible to guess at the affinities of the animals. Further, several important groups are already represented in some of the oldest of the fossil-bearing rocks at present known, and the differentiation of these groups must have taken place in the dark ages before the record of the fossils begins. In spite of these disadvantages, however, the study of fossil Crustacea does throw considerable light on the evolution of the group, and it is likely that interesting results in this direction await future investigations.

In the earliest fossiliferous rocks the most abundant and important Arthropods are the Trilobites (Fig. 81), an extinct group which appears to have been related to the primitive Crustacea. The name Trilobite refers to the three-lobed form of the body when seen from the dorsal side, most species having a pair of grooves running lengthwise which divide off a middle lobe containing the principal organs of the body from two lateral "pleural" expansions covering the limbs. The head-shield shows indications of being composed of five segments, and bears a pair of sessile compound eyes. It is followed by a number (up to twenty-six) of free somites, and the body ends in a tail-shield, or "pygidium," which is often plainly composed of several somites fused together. Although Trilobites are among the commonest and most familiar of fossils in the older rocks, the nature of their appendages remained quite unknown until within recent years, when specimens of several species showing the structure of the limbs and under-side of the body were discovered in America. From these it appears that the head bore in front a pair of long thread-like antennæ and four pairs of two-branched appendages, each with a jaw process, or "gnathobase," turned towards the mouth, which is covered below by a large anterior lip, or "hypostome." It seems probable that the five pairs of head-appendages correspond respectively to the antennules, antennæ, mandibles, maxillulæ, and maxillæ, of Crustacea; but the second pair appear to have acted as jaws, retaining the gnathobase which, among Crustacea, is only hinted at by the hooked spine on the antenna of the nauplius larva.

Each of the free somites and of those forming the tail-shield bears a pair of two-branched appendages, not differing greatly from the posterior appendages of the head, but becoming smaller and more flattened towards the hinder end of the body. The numerous genera and species of Trilobites present great differences in the form and ornamentation of the dorsal surface of the body, and it is probable that considerable differences may also have existed in the structure of the limbs, which are only known in two or three species. Some Trilobites are among the most ancient of known fossils, being found in rocks of the Lower Cambrian epoch. The group reaches its maximum development in the Ordovician, and the number of the species and size of the individuals gradually diminish through the Silurian and Devonian till they become extinct at the close of the Carboniferous epoch, except for a single species found in rocks of Permian age in America.

Although zoologists are not all agreed as to the precise systematic place to be assigned to the Trilobites, there can be little doubt that they were related more or less closely to the most primitive Crustacea, and they are of special interest as preserving for us the stage in which the second pair of appendages were still used as biting jaws, and had not moved forwards in front of the mouth to become antennæ, as in all living Crustacea.

Contemporary with some of the earliest Trilobites, however, are undoubted Crustacea, which, so far as we know their structure, are not very different from types now living. In the Cambrian epoch the Branchiopoda appear to be represented by _Protocaris_, which in its general form resembles _Apus_; and there are a variety of genera and species of Ostracoda, although, since their shells alone are preserved, it is not possible to determine their exact relations to existing forms. In the succeeding Ordovician and Silurian epochs we first meet with the remains of Barnacles, and it is interesting to note that some of them are referred to the genera _Pollicipes_ and _Scalpellum_, which are represented by numerous species in the seas of the present day. Along with these, however, are some strange-looking forms (_Turrilepas_, etc.), having the body covered with rows of overlapping plates. If these are really Cirripedes, they must have differed considerably in structure from the more modern types.

The Malacostraca are more interesting from the point of view of palæontology than the other subclasses of Crustacea, since the evolution of the group appears to have taken place within the period covered by the fossil records, and it is possible to trace the course of that evolution--at least, in its broad outlines. It has already been pointed out that the most primitive of existing Malacostraca are the Phyllocarida (_Nebalia_ and its allies), which are in several respects intermediate between the higher Malacostraca and the Branchiopoda; and it is interesting to find that fossils apparently belonging to the Phyllocarida are found far earlier than any of the other Malacostraca. In the Cambrian, and more abundantly in the Ordovician and Silurian, there are found Crustacea (Fig. 82) that resemble _Nebalia_ in having a large bivalved carapace, with a movable beak-like plate in front, a projecting abdomen without conspicuous limbs, and a pair of large spines at the sides of the telson. Unfortunately, we have almost no knowledge of the structure of the limbs; but it can hardly be doubted that these very ancient Crustacea were allied to the existing Phyllocarida, and that they included the forerunners of the higher Malacostraca.

It is in the Carboniferous epoch, in all probability, that we must look for the origin of most of the existing orders of Malacostraca. In the rocks of this age in different parts of the world there have been found a number of undoubted Malacostraca, nearly all of the shrimp-like form which there is good reason to believe to be a primitive characteristic. Some of these (_Pygocephalus_--Fig. 83) have recently been shown to possess a brood-pouch formed of overlapping plates on the under-side of the thorax, and thus resemble the existing Mysidacea, which stand at the base of the Peracaridan series of orders. Others have a pair of strong side-spines near the tip of the telson, and in other ways resemble the recent Euphausiacea, so that they may have been primitive members of the Eucaridan series.

Among the Crustacea of the Carboniferous and Permian epochs, there are a number of forms of which the affinities were until recently quite obscure. They have two-branched antennules, a scale-like exopodite on the antenna, and the last pair of appendages (uropods) form, with the telson, a tail-fan. In these points they resemble the shrimp-like forms, but there is no carapace, and all the somites of the thorax are distinct, so that the form of the body is rather that of an Amphipod or Isopod. On the discovery of the remarkable Crustacean _Anaspides_ (Fig. 84), which lives in fresh-water pools in the mountains of Tasmania, it was pointed out that it agreed with the fossil genera _Uronectes_, _Palæocaris_, and their allies, in those very characters in which they differed from all other Crustacea, and that it must be regarded as a surviving representative of the ancient group to which the name of Syncarida had been given. The more recent discoveries of living forms, _Paranaspides_ from the Great Lake of Tasmania and _Koonunga_ from fresh-water pools near Melbourne, and of the fossil _Præanaspides_ (Fig. 85) from the Coal-measures of Derbyshire, have tended to support this conclusion. There can be little doubt that the Syncarida arose during the Carboniferous epoch (or earlier) from primitive shrimp-like forms which lost the carapace; but, after flourishing for a relatively brief period, the group dwindled away, although a few survivors have lingered on, like so many other "living fossils," in the isolated Australian region.

It must be pointed out that, in spite of the resemblance of the body of _Anaspides_ to that of an Amphipod, the Syncarida can have had no close relation to the origin of the Isopoda and Amphipoda. These have also been derived from a shrimp-like type, but their possession of a brood-pouch, among other characters, shows that they are linked on to the Mysidacea, and must have arisen from some primitive member of that group, like _Pygocephalus_. Although palæontology as yet gives little help in tracing the course of their evolution, we can imagine what the intermediate links must have been like by comparison with the living Cumacea and Tanaidacea.

It is possible, indeed, that the divergence of the Isopod line of descent from that of the Mysidacea took place earlier than the Carboniferous epoch, for there has recently been discovered in rocks of Devonian age in Ireland a single specimen of a fossil, to which the name of _Oxyuropoda_ has been given, which has every appearance of being an Isopod. At all events, undoubted Isopods make their appearance in rocks of the Secondary Period, and some of those from the Jurassic epoch are not very different in general form from types still existing.

Some of the Carboniferous shrimp-like Crustacea present characters which seem to point in the direction of the Stomatopoda, and fossils which clearly belong to that group are found in Jurassic and later deposits. In the Cretaceous epoch there were Stomatopoda resembling modern types so closely that they have been referred to the existing genus _Squilla_. We are even able to say that they resembled the living Stomatopoda in their mode of development, for larvæ of the type known as _Erichthus_ have been recognized in rocks of Cretaceous age from Lebanon. This is a striking example of the way in which, by a fortunate accident as it were, organisms apparently ill-adapted for fossilization may occasionally be preserved.

Of the Decapoda the geological history is tolerably full, and it is possible to trace in its broad outlines the course of evolution of the various suborders. Here again it is likely that the beginnings of the group are to be sought for in the Carboniferous epoch, and some of the obscure shrimp-like forms of that age show hints of an affinity with the Decapods. In the Triassic epoch, however, and more abundantly in the succeeding Jurassic, a number of types are found which seem to include primitive representatives of several of the existing groups of Natantia and Reptantia. It is noteworthy that among them are some forms (_Æger_, etc.) resembling the existing Stenopidea, a tribe which in some respects is intermediate between these two suborders. In the Stenopidea the first three pairs of legs bear pincer-claws, as in the Lobster, but the third pair is much the largest; and _Æger_ agrees with them in this unusual character, though there is little else, in what is known of its structure, to help to determine its affinities.

The tribe Penæidea, which occupies in many respects a primitive place among the Natantia, is abundantly represented in the Jurassic epoch, especially in the lithographic stone (Upper Jurassic) of Solenhofen, and by somewhat doubtful specimens from the earlier Trias. All these agree in having the first three pairs of legs with pincer-claws, and not differing greatly in size. Some of the Jurassic and later fossils are of so modern a type that they have been referred to the existing genus _Penæus_.

The Upper Jurassic rocks also preserve the earliest undoubted specimens of true Prawns of the tribe Caridea, and some of these show swimming branches (exopodites) on the thoracic legs, so that they were probably related to the primitive family Acanthephyridæ, of which the existing members are found in the deep sea. It is possible, however, that Caridea were already in existence far earlier, for some of the obscure Carboniferous forms seem to have the broadened side-plates of the second abdominal somite, which, so far as we know, are exclusively characteristic of that tribe.

The Reptantia, forming the other large division of the Decapoda, also had their origin at least as early as the Triassic epoch, where representatives of the tribes Eryonidea and Scyllaridea are found. The history of the Eryonidea has already been discussed (p. 133) in dealing with the deep-sea Crustacea. The oldest representatives of the Scyllaridea belong to a family (Glyphæidæ) now wholly extinct, and are in many respects more primitive and lobster-like than any of the living Spiny Lobsters and their allies (Palinuridæ and Scyllaridæ). Forms with greatly thickened antennæ, indicating a transition to the Palinuridæ, begin to appear in the Jurassic; and in the later Cretaceous a genus, _Podocrates_, occurs which is hardly to be distinguished from _Linuparus_, now living in Japanese seas. The Scyllaridæ have the antennæ modified into broad shovel-like plates, and perhaps take their origin from _Cancrinus_, in the Solenhofen lithographic stone (Jurassic), which has broad and apparently flattened antennæ. True Scyllaridæ are certainly found in Cretaceous deposits, and some, from the Upper Chalk, are even referred to the existing genus _Scyllarus_.

The Anomura are almost unknown as fossils, but the true Crabs, or Brachyura, are abundantly represented. They first appear about the middle of the Jurassic epoch, and, as already pointed out, the earliest forms (Prosoponidæ) are referred to the Dromiacea, and appear to be closely related to the primitive Homolodromiidæ now living in the deep sea (p. 134). One of the oldest, and at the same time one of the most completely known, is _Protocarcinus_, from the Great Oolite of Wiltshire, which is preserved (in the only known specimen) with the abdomen partly extended, possibly indicating that the abdomen was less closely doubled under the body than in modern Crabs.

The next group of Crabs to appear are the Oxystomata, which are found from the middle of the Cretaceous epoch onwards. The Brachyrhyncha perhaps begin to appear about the same time, but the affinities of the earlier types are doubtful, and it is only in the Tertiary that they become abundant and unmistakable. Several living genera, such as _Cancer_, date back to the Eocene. The Spider Crabs (Oxyrhyncha) are rare as fossils, and the earliest specimens are found near the beginning of the Tertiary.

APPENDIX

I. METHODS OF COLLECTING AND PRESERVING CRUSTACEA

It may be useful to give here a few hints as to the methods of collecting Crustacea. Of the species that live in the sea, many may be found between tide-marks by turning over stones and searching among sea-weeds and in rock crevices. A small hand-net, made by fastening a bag of coarse muslin to a stout wire ring of a few inches diameter, is useful for fishing in rock pools. Shore-collecting in this manner is most productive at spring-tides, when the deeper levels of the shore are open to exploration.

Many burrowing species are to be found by digging in the sand near low-water mark. In addition to Crabs and other large species, many minute forms, Amphipods, Cumacea, and the like, inhabit such localities. The best way of collecting these is to stir up a spadeful of the sand in a bucket of water, and, after allowing the sand to settle for a few seconds, to pour off the water through a muslin bag. After repeating the operation two or three times, the contents of the bag are washed out into a jar or dish of sea-water for examination with a lens or under the microscope.

Dredging is the most effective method of obtaining Crustacea that live in deeper water. The dredge usually employed by naturalists consists of a heavy rectangular iron frame to which is attached a strong bag-shaped net. The two longer sides of the frame are sharp-edged and bevelled outwards, so as to "bite" when the dredge is dragged along the sea-bottom. To the shorter sides are hinged a pair of arms ending in rings. The dredge-rope is made fast to one of these rings, while the other is held only by a "stopping" of yarn, which gives way if the dredge should catch on a rock, and permits it to be dragged sideways off the obstruction. The size and weight of the dredge may vary according to the depth at which it is to be used and the power available for working it. A convenient size for use with a small sailing boat at moderate depths has a frame 20 by 5 inches.

Apart from dredging, many specimens from moderately deep water may be picked out from among the "rubbish" brought up on fishermen's lines or by the trawl, and various Crustacea besides the edible species find their way into Lobster and Crab pots. The true deep-sea fauna is, for the most part, only to be reached by specially-equipped expeditions, although specimens from great depths are occasionally obtained during the operations for the repair of submarine telegraph cables.

The floating animals of the surface of the sea are to be captured by means of the tow-net. This consists of a conical bag of muslin, cheese-cloth, or, best of all, silk "bolting-cloth," attached to a galvanized iron-ring of one or two feet in diameter, and having a zinc can or a strong glass jar fixed to the narrow end. The ring is attached by three equidistant cords to the towing line, and the net is towed slowly at or near the surface of the sea. When taken on board, the contents of the can are emptied into a jar of sea-water for examination. The tow-net is best used when there is only enough way on the boat to keep the net from sinking; if towed more rapidly, delicate organisms are apt to be crushed by the pressure of the water, or the net itself may be burst. The use of unnecessarily fine nets should be avoided. A fine-meshed net may not capture a single specimen of the larger Crustacea, even though these may be swarming in the water through which it is drawn.

By weighting the tow-net it may be used at various depths to capture the floating animals of mid-water. When it is so used, however, it is impossible to tell from what depth any particular specimen may have come, since it may have been captured during the hauling in of the net. For more precise investigations in deep water, "closing tow-nets" of various types have been devised, which can be opened by a "messenger" sent down the line when the net has reached the desired depth, and closed again by another "messenger" before it is hauled in.

A simple method that has proved very successful for collecting small Crustacea living on a sandy bottom in shallow water is to employ a light tow-net with a cane ring, and with a heavy sinker attached to the towing line at a distance of a few feet in front of the net. As the sinker is dragged along the bottom, the net floats up behind it, and catches small animals stirred up by its passage.

For collecting the smaller fresh-water Crustacea--Water-fleas and the like--a small muslin ring-net may be used in ponds and ditches. The plankton of the open water of lakes is best obtained by means of a tow-net like that described above for use in the sea.

The interesting blind species known as "Well Shrimps" are to be looked for in the water of springs and wells. In wells fitted with a pump, Professor Chilton found that "the Crustacea are often brought up most abundantly when pumping is first commenced, and that jerking the handle of the pump somewhat violently is often more successful than pumping at the ordinary rate." In disused open wells, they may be trapped by baiting a muslin ring-net with a piece of stale meat or fish, and pulling it up rapidly after it has remained in the well for a few hours. The subterranean waters of caves have yielded many curious species in various parts of the world. For the capture of species living in the deep water of large lakes, a special form of dredge has been devised with runners to prevent it from sinking into the soft mud, while the mouth of the net is raised a few inches above the bottom.

For preserving Crustacea the best medium to use is 70 per cent. alcohol. Strong spirit diluted with a little less than one-third its bulk of water gives about the required strength. If too strong spirit is used, the specimens tend to be hard and brittle, and delicate organisms become shrivelled. Methylated spirit as sold in the shops in this country contains mineral naphtha, and turns milky when water is added, so that it is unsuitable for preserving specimens. Methylated alcohol without naphtha can be bought, by permission of the Inland Revenue authorities, but only in considerable quantities at a time.

Formalin is very cheap and readily obtained, but it is much less suitable than spirit for most Crustacea, as it tends to make them stiff and fragile, and small forms containing much lime, such as Cumacea, may become decalcified. For Crustacea collected by the tow-net, however, formalin gives good results. A few drops of strong formalin, added to the water into which the tow-net has been washed, kills the animals in a few minutes. After they have sunk to the bottom, the liquid may be poured off and replaced by formalin diluted with sea-water (for marine plankton), or by a mixture of formalin and spirit. The most suitable strength of formalin varies with different organisms, but 5 per cent. (_i.e._, 1 part of commercial formalin to 19 parts of water) is perhaps most generally useful.

Crabs, Prawns, and the like, if put alive into strong spirit, may throw off some of their limbs, or else become so rigid that these break on the slightest manipulation. This may often be avoided by killing the animals in weak spirit (30 per cent. or less) before preserving in strong spirit. Marine species may also be killed by placing them in fresh water, care being taken not to allow them to remain in it longer than is necessary, as it causes distortion of the membranous appendages.

The larger Crabs, Lobsters, and the like, may be preserved dry, although in this state they are unsuitable for examination of the more delicate appendages. The carapace should be detached, and the soft parts cleaned away as far as possible, a bent wire being used, if necessary, to remove the flesh from the legs. The specimens should be dried in the shade, to preserve as much as possible of the natural colour.

With specimens intended for permanent preservation in spirit, the use of corks should be avoided, as they discolour the spirit, and ultimately the specimens. Small specimens are most conveniently kept in glass tubes closed with a piece of clean elder-pith (not cotton-wool), and placed, upside down, in a bottle of spirit. Labels to be placed inside the tubes are best written with Indian ink, and allowed to dry before immersion in the spirit.

II. NOTES ON BOOKS

The literature of Carcinology is bewildering in its extent, and is for the most part scattered through the volumes of scientific periodicals and the publications of learned societies in most of the languages of Europe. A guide to the current literature is provided by the _Zoological Record_, the latest volume of which, relating to the year 1909, enumerates no fewer than 337 papers dealing wholly or in part with this group of animals.

The following short list of books in the English language may be of some help to the beginner. Most of them give references to the literature which will provide the necessary guidance towards a further study of the subject.

GENERAL WORK

_Huxley, T. H._ The Crayfish: an Introduction to the Study of Zoology. International Science Series, vol. xxviii. London, 1880.

_Stebbing, T. R. R._ A History of Crustacea: Recent Malacostraca. International Science Series, vol. lxxiv. London, 1893.

_Calman, W. T._ Crustacea. A Treatise on Zoology, edited by Sir Ray Lankester. Part vii., fascicle iii. London, 1909.

_Smith, G._, and _Weldon, W. F. R._ Crustacea. The Cambridge Natural History, vol. iv. London, 1909.

_Lister, J. J._ Crustacea, in "A Student's Textbook of Zoology," by Adam Sedgwick. Vol. iii. London, 1909.

BRITISH CRUSTACEA

_Baird, W._ The Natural History of the British Entomostraca. (Ray Society.) London, 1850.

_Bell, T._ A History of the British Stalk-eyed Crustacea. London, 1853.

_Spence Bate, C._, and _Westwood, J. O._ A History of the British Sessile-eyed Crustacea. 2 vols. London, 1863 and 1868.

_Brady, G. S._ A Monograph of the Free and Semiparasitic Copepoda of the British Islands. (Ray Society.) 3 vols. London, 1878-1880.

These works, although still valuable, and indeed indispensable, are now more or less out of date. A list of British Malacostraca (except Amphipoda) will be found in Mr. Stebbing's volume mentioned above.

_Sars, G. O._ An Account of the Crustacea of Norway. Vol. i., Amphipoda, 1890-1895. Vol. ii., Isopoda, 1896-1899. Vol. iii., Cumacea, 1899-1900. Vols. iv. and v., Copepoda, 1903 (in progress). Christiana and Bergen.

A very large proportion of the British species in the groups mentioned are described and figured in this splendid series of volumes. The text is in English.

_Norman, A. M._, and _Scott, T._ The Crustacea of Devon and Cornwall. London, 1906.

_Webb, W. M._, and _Sillem, C._ The British Woodlice. London, 1906.

Memoirs of the Liverpool Marine Biology Committee, edited by Professor _W. A. Herdman_. A useful series of monographs on the structure and life-history of common British marine animals and plants. The following relate to Crustacea:

Memoir VI. Lepeophtheirus and Lernæa (Parasitic Copepoda). By _A. Scott_. 1901.

Memoir XII. Gammarus (Amphipod). By _M. Cussans_. 1904.

Memoir XIV. Ligia (Isopod). By _C. G. Hewitt_. 1907.

Memoir XVI. Cancer (Edible Crab). By _J. Pearson_. 1908.

Descriptions of all the British species of Barnacles will be found in _Darwin's_ "Monograph of the Sub-class Cirripedia." (Ray Society.) 2 vols. London, 1851-1854.

INDEX

Abdomen of Lobster, 6

Abyssal fauna of lakes, 185

Acanthephyridæ, 268

Acorn-shells, 41

_Æga_: in Sponges, 210; parasitic on fish, 219

_Æger_, 267

_Æglea_, 181

Air-breathing Crabs, 188

_Albunea_, 102

Alcock, A.: on habits of _Ocypode_, 105; on temperature of sea, 120; on eyes of deep-sea Crustacea, 124; on colour in deep-sea Crustacea, 127; on luminosity of deep-sea Crustacea, 125, 126; on eggs of deep-sea Prawn, 130; on _Nephrops_, 132; on habits of _Coenobita_, 194, 195

Allen, E. J., on Mackerel fishery, 251

Alpheidæ, 211

American Lobster, 32

Amphibious Crustacea, 104, 188

Amphipoda, 52; seashore, 95, 107; plankton, 145; terrestrial, 189; fresh-water, 172; in Sponges, 210; on Jellyfishes, 212; and Hermit Crabs, 215; parasitic, 223; wood-boring, 255

_Amphithoë_, 95

_Anaspides_, structure and fossil allies, 264

Andrews, C. W.: on Land Crabs, 190; on habits of _Coenobita_, 195; on habits of _Birgus_, 197, 198

_Anomalocera_, 150

Anomura, 60; fresh-water, 181

Anostraca, 36; habits, 162, 164

Antennæ of Lobster, 8, 14; use in respiration in _Corystes_, 100; in _Albunea_, 102

Antennule of Lobster, 8, 14

Ants, Woodlice living with, 205

_Apseudes_, 50

_Apus_, 36; habitats, 161; occurrence in Britain, 162; habits, 163; hæmoglobin in, 165; fossil allies of, 260

Appendages of Lobster, 8; of Trilobites, 259

_Aratus_, 189

_Argulus_, 41

Aristotle on Shrimp living with Mollusc, 218

_Armadillidium_, 203

_Artemia_: larvæ of, 81; habitat, 164

Arthropoda, 2; classification, 204

_Asellus_, 172; destroying fishing nets, 253

Astacidæ, 176

_Astacoides_, 178

_Astacopsis_, 177; used for food, 243

Astacura, 60

_Astacus_: habits, 174; young, 76; distribution, 177; used for food, 241

Asymmetry of Lobster, 29

Atyidæ, 179; used for food, 248

Autotomy, 113; in Lobster, 30

Baikal, Lake, 182

_Balanus_, 42; larvæ, 83; habits, 114; used for food, 237; cultivated for manure, 250

Barnacles, 41; development, 83; seashore, 114; of high seas, 155; on Whales, Turtles, and Crabs, 209; parasitic, on fish, 235; used for food, 237; cultivated for manure, 250; fossil, 261

_Bathynomus_, 131

Beach-fleas, 107

Bell, T., on development of Land Crabs, 193

"Berry," Lobster in, 28

Bipolarity, 132

_Birgus_, 94; habits and structure, 195; breeding habits, 199. See also Robber Crab

Bloodvessels of Lobster, 17

Blue Crab, 249

_Bopyroides_, 221

_Bopyrus_, 221

Borradaile, L. A.: on habits of _Remipes_, 102; on _Huenia_, 110; on larvæ of Robber Crab, 199

Bouvier, E. L., on Dromiacea, 134

Brachygnatha, 63

Brachyrhyncha, 64; fossil, 270

Brachyura, 62; fossil, 269

Brain of Lobster, 20

Branchiopoda, 35; larvæ, 80; habitats, 161; fossil, 260

Branchiostegite, 18

_Branchipus_, 165

Branchiura, 41

Brine Shrimp, 164; larvæ, 81

Brood-pouch of Peracarida, 46

Brown Shrimp, 244

Browne, F. Balfour, on _Apus_ in Scotland, 162

Browne, Patrick, on Mountain Crab, 193

Bullen, G. E., on food of Mackerel, 251

_Bythotrephes_, 168

Caligidæ, 225

_Caligus_, 225

_Callianassa_, 103

_Callinectes_, 249

_Calocalanus_, 149

_Cambaroides_, 177

_Cambarus_: distribution, 177; habits, 178; blind species, 185; used for food, 243

_Cancer_: used for food, 248; fossil, 270. See also Edible Crab

_Cancrinus_, 269

_Canthocamptus_, 170; resting stage, 171

_Caprella_, 54

Caprellidæ, 55; habits, 109

Carapace of Lobster, 6, 9

_Carcinus_: larval stages, 68; habits, 107. See also Shore Crab

_Cardisoma_, 191

Caridea, 59; zoëa of, 73; fossil, 268

_Caridina_, 248

Carp-lice, 41

Caspian Sea, 182

Caudal fork, 40

Cephalothorax of Lobster, 8

_Ceratiocaris_, 262

_Chalimus_, 225

Chela of Lobster, 12

Cheliped of Lobster, 8

_Chelonobia_, 155, 209

_Chelura_, 255

_Cheraps_, 177

Chilton, C., on Woodlice in New Zealand, 206

_Chirocephalus_, 35, 161

Chitin, 15

_Chondracanthus_, 228

Chromatophores, 31, 110

Chun, C., on eyes of plankton Crustacea, 154

_Chydorus_, 165

_Cirolana_, 218

Cirripedia, 41; development, 82; on Whales, 209; parasitic, 231; fossil, 261. See also Barnacles

Cladocera, 37; development, 80; habits, 165; in plankton of lakes, 168; absence from Tanganyika, 184

Claspers of _Chirocephalus_, 35

Classification of Crustacea, table, 34; of Decapoda, table, 58

Close time for Lobsters, 239

Coconut Crab. See Robber Crab

Cocoons of Copepoda, 171

_Coenobita_: habits, 194; respiration, 195

Coenobitidæ, 61; habits, 194

Colour of Lobster, 31; deep-sea Crustacea, 127; plankton Crustacea, 150; Branchiopoda, 165; subterranean Crustacea, 187

Colour-change, 110

Columbus and Gulf-weed Crab, 155

Commensalism, 207

_Conchoderma_, 209

_Conchoecia_, 144

Conchostraca, 37; habits, 163

Convergent evolution, 205

Copepoda, 40; development, 82; of open sea, 140; plankton, 149; luminosity, 150; eyes, 152; of fresh water, 170; of Tanganyika, 184; and Hermit Crabs, 215; parasitic, 224; as food of Mackerel, 250

_Copilia_, 152

Coral of Lobster, 27

Corals, Crustacea on, 210

_Coronula_, 155, 209

Corycæidæ, 152

_Corystes_, 99

Crabs: true, 62; sand-burrowing, 99; of fresh water, 179; of Tanganyika, 183; on Corals, 211; carrying Sea-anemones, 215; living with Molluscs, 217; living in Sea-urchin, 218; Isopods parasitic on, 223; Rhizocephala parasitic on, 231; used for food, 248; fossil, 269. See also Shore Crab, Edible Crab, etc.

_Crangon_, 59; habits, 97; fishery, 244

Crawfish, Sea-, 59

Crayfish: young of, 76; habits, 174; distribution, 176; terrestrial, 178, 189; blind, in caves, 185; in British Isles, 241; used for food, 241; disease of, 243

Cumacea, 48; habits, 98; of deep sea, 129; of plankton, 141

Cunningham, J. T., on development of Land Crabs, 192

Cup Shrimps, 245

Cyamidæ, 56; habits, 224

_Cyclops_, 40; nauplius, 82; habits, 170; resting stage, 171; as host of Guinea-worm, 252

_Cymothoa_, 220

Cymothoidæ, habits, 218

Cymothoinæ, habits, 220

_Cypris_, 38; reproduction, 172

Cypris stage of Barnacles, 84; of _Sacculina_, 233

_Cystisoma_, 145

_Cythereis_, 38

_Daphnia_, 38; development, 81; habits, 165; in plankton of lakes, 168

Darwin, C.: on fresh-water fauna, 157, 159; on habits of _Birgus_, 198, 199; on Barnacles used for food, 237

Decapoda, 57; fossil, 267

Deep-water Prawn, 246

Delage, Y., on development of _Sacculina_, 232

Development of Lobster, 28; of Crayfish, 77; of River Crab, 78; of Peracarida, 78; of Woodlice, 79; of Opossum Shrimp, 79; of Cladocera, 80; of Ostracoda, 81; of Copepoda, 82; of fresh-water Crustacea, 160; of Epicaridea, 223; of parasitic Copepoda, 225, 227, 230; of Rhizocephala, 232

_Diaptomus_, 170

_Diastylis_, 49

Diatoms, 139; relation to Mackerel fishery, 251

_Dichelaspis_, 209

Digestive gland, 17

Dispersal of fresh-water Crustacea, 159; of Crayfishes, 174

Distribution of Woodlice, 206

Doflein, F., on luminosity in marine animals, 126

Dogfish, Barnacle parasitic on, 235

_Dorippe_, 95

_Dracunculus_, 252

_Dromia_, 63; habits, 96; and Sponge, 215

Dromiacea, 63; of deep Sea, 128, 134

Dublin Prawn, 33; fishery, 240

_Ebalia_, 63; protective resemblance, 109

Écrevisse, 242

Edelkrebs, 242

Edible Crab, 64, 248

Eggs of Lobster, 27; of deep-sea Crustacea, 130; of fresh water Branchiopoda, 161

Endopodite, 11

_Engæus_: distribution, 177; habits, 179, 189

Entoniscidæ, 223

Ephippium of Cladocera, 167

Epicaridea, habits, 221

Epiplankton, 143

Epipodite, 11

Epistome, 62

_Erichthus_ larva, fossil, 266

_Eryon_, 135

Eryonidea, 60; eye-stalks of, 122; luminosity, 126; eggs of, 131; fossil and living species, 133, 268

_Estheria_, 36; habitats, 161

Eucarida, 56

Eucopepoda, 41

Eumalacostraca, 45

_Eupagurus_, 91; commensals, 213

Euphausiacea, 56; larvæ, 76; of deep sea, 124, 125; luminous organs, 125, 151; eyes, 153; fossil, 263

European Lobster, 32

_Eurydice_, 219

Evolution, 256

Excretory organs, 19

Exopodite, 10

Exoskeleton, 15

Eyes of Lobster, 20; of _Cyclops_, 40; of deep-sea Crustacea, 121; of plankton Crustacea, 151; of _Bythotrephes_, 169; degeneration in subterranean Crustacea, 186

Eye-stalk of Lobster, 14

Fairy Shrimp, 35; habitats, 161

_Filaria_, 252

Fiddler Crab: habits, 106; colour-change, 111

Fish: attacked by Isopods, 219; Crustacea as food of, 250

Fish-lice, 224

Flagellum, 14

Foraminifera, 118

Fossil Crustacea, 256

_Galathea_, 130

Galatheidea, 60

Galls on Corals, 211

Gamble, F. W., on colour-changes, 111

Gammaridea, eyes of, 154

_Gammarus_, 53; distribution, 172; in Lake Baikal, 183

Ganglia of Lobster, 20

Garstang, W., on habits of Masked Crab, 100

Gastric Mill of Lobster, 17

Geographical distribution of Lobsters, 32; of Crayfishes, 174

Gecarcinidæ, 190

_Gecarcinus_, 190; supposed metamorphosis, 192

_Gecarcoidea_, 190

_Gelasimus_, 188; habits, 106; colour-changes, 111

Generative organs of Lobster, 27

Giant Crab, 64

Giesbrecht on luminosity of Copepoda, 150

Gill chamber of Lobster, 18

Gills of Lobster, 12, 18; of Mysidacea, 48

Globigerina ooze, 119

_Glomeris_, a Millipede, 3, 203

Glyphæidæ, 268

Gnathobases of Trilobites, 259

_Gnathophausia_, 48

Goose Barnacle, 42

Gosse, P. H., on Porcelain Crabs, 115

Grapsidæ, 180

_Grapsus_, 107

Green gland, 19

Gribble, 253

Guilding, L., on development of Land Crabs, 193

Guinea-worm, 252

Gulf-weed Crab, 155; on Turtles, 208

Habitations of shore Crustacea, 95

_Hæmocera_, 229

Hæmoglobin in Branchiopoda, 165

Hairs of Lobster, 22

Hall. See Spencer and Hall

Halocypridæ, 141, 144; luminosity, 151

_Hapalocarcinus_, 211

Head of Lobster, 7

Hearing, sense of, in Lobster, 22

Heart of Lobster, 17

Hermaphroditism of Cirripedia, 43; in Isopoda, 52; of Cymothoinæ, 221; of Epicaridea, 223; of Rhizocephala, 231

Hermit Crabs, 61; of seashore, 91; of deep sea, 124, 136; terrestrial, 194; commensals, 213; Isopods parasitic on, 221

_Heterocarpus_, 125

Hickson, S. J., on _Caridina_, 248

_Hippa_, 102

Hippidea, 62; habits, 102

_Hippolyte_, colour-changes, 111

_Holopedium_, 170

Homaridæ, 33

_Homarus_, 32; fishery, 238

Homolodromiidæ, 134; fossil allies, 269

Homologous organs, 10

Hoplocarida, 64

_Huenia_, 109

Huxley, T. H.: on Barnacles, 115; on distribution of Crayfishes, 176

_Hyas_, masking habits, 96

_Hyperia_, 142; on Jellyfishes, 212

Hyperiidea, 141; eyes, 154

Hypoplankton, 143

Hypostome, 259

_Inachus_ infected with _Sacculina_, 235

Intestine of Lobster, 16

Isopoda, 51; deep-sea, 131; fresh-water, 172; subterranean, 186; land, 199; in Sponges, 210; parasitic, 218; wood-boring, 253; fossil, 266

_Jasus_, 241

Jellyfishes, Amphipods on, 212

Keeble, F., on colour-changes, 111

Kidney, 19

_Koonunga_, 264

Land Crabs, 189; injuring crops, 253

Land Hermit Crabs, 194

Land-hoppers, 189

Langouste, 241

Lankester, E. Ray, on hæmoglobin in Branchiopoda, 165

Larvæ of Lobster, 28; of Norway Lobster, 71; of Stomatopoda, 80; of Brine Shrimp, 81; of Land Crabs, 191; of Robber Crab, 199; fossil, of Stomatopoda, 266

Larval stages, 66; significance of, 85

_Latreillia_, 128

Leach, W. E., on the Gribble, 254

_Leander_, 59, 179; Isopod parasitic on, 221; used for food, 245

Legs of Lobster, 8, 12

_Lepas_, 42; habitat, 155; nauplius, 148

_Lepeophthirus_, 225

_Leptodora_, 169

Leptostraca, 45

_Lernæa_, 226

Leucosiidæ, 109

_Ligia_, structure and habits, 200

_Limnoria_, 254

_Linuparus_, 269

_Lithodes_, 62, 94

Lithodidæ, 61

Liver of Lobster, 17

Lobsters: deep-sea, 121; fishery, 238

Lovén, S., on relict Crustacea, 181

Luminosity of deep-sea Crustacea, 125; of plankton Crustacea, 150

Lynceidæ, 165

Mackerel feeding on plankton, 250

_Macropodia_, masking habits, 97

_Maia_, masking habits, 96

Malacostraca, 43; fossil, 261

Mammoth Cave, Crayfish of, 185

Mandible of Lobster, 8, 14

Masked Crab, 99

Masking of Crabs, 96, 215

Maxilla of Lobster, 8; of _Argulus_, 41

Maxillipeds of Lobster, 8, 11

Maxillula of Lobster, 8

Medusæ, Amphipods on, 212

Megalopa of Shore Crab, 70

_Meganyctiphanes_, 56, 151

_Melia_, 215

_Mesidotea_, 181

Mesoplankton, 143

Messmates, 208

Metamorphosis of Lobster, 28; of Land Crabs, 191

Metanauplius of _Penæus_, 75

Mimicry, 204

_Mimonectes_, 145

Mitsukuri, K., on cultivation of Barnacles, 250

Mole Crabs, 102

Monstrillidæ, 230

Moulting of Lobster, 15; of Woodlice, 206

Mountain Shrimps, 181; structure and fossil allies, 264

Mouth-frame of Crabs, 62

Müller, Fritz: on larval stages of _Penæus_, 73; on habits of _Aratus_, 189

Müller, O. F., on Nauplius, 82

_Munida_, larva of, 71

_Munidopsis_: eyes, 123; eggs, 130

Murray River Lobster, 243

Mussels and Pea Crab, 217

Myodocopa, 39

Mysidacea, 46; development, 79; luminosity, 127; eyes, 153; and Hermit Crabs, 215; fossil, 263

_Mysis_, 47; in lakes, 181, 182

Natantia, 58; used for food, 243

Nauplius of _Penæus_, 73; of Crayfish, 79; of Opossum Shrimp, 79; of Branchiopoda, 80; of _Cyclops_, 82; of Ostracoda, 82; of Barnacles, 83; of _Lepas_, 148; of _Leptodora_, 170; of _Sacculina_, 233; eye, 40

_Nebalia_, 44; fossil allies, 261

Nebaliacea, 44

Necton, 138

Nematocarcinidæ, 128

_Nephrops_, 33; larva, 71; distribution, 132; fishery, 240

Nephropsidea, 33, 60

_Nephropsis_, 121

_Neptunus_, 156; used for food, 249

Neritic plankton, 141

Nervous system of Lobster, 20

_Niphargus_, 184

Northern Crayfishes, 176

Norway Lobster, 33; larva, 71; fishery, 240

Norwegian Prawn, 246

Notostraca, 36; habits, 162

Oceanic plankton, 141

Octopus preying on Crustacea, 89

_Ocypode_, 188; habits, 104; carnivorous, 195

Olfactory filaments of Lobster, 25

_Oniscus_, 51; Structure and habits, 201

Operculata, 43

Opossum Shrimps, 46; development of, 79

_Orchestia_, 107

Orientation, organs of, 24

Ostracoda, 38; development, 81; luminosity, 127, 151; plankton, 144; fresh-water, 172; of Tanganyika, 184; fossil, 261

Ovary of Lobster, 27

Oxyrhyncha, 64; masking habits, 96; fossil, 270

Oxystomata, 63; habits, 101; protective resemblance, 109; deep-sea, 128; fossil, 269

_Oxyuropoda_, 266

Oyster Crab, 249

Oysters and Pea Crab, 217

Paguridea, 61

_Paguropsis_ and Sea-anemones, 214

_Palæmon_, 179; used for food, 248

_Palæmonetes_, 174

Palinura, 59

Palinuridæ, 241; fossil, 269

_Palinurus_, larva of, 72; fishery, 240

Palp, 14

_Pandalus_, 59, 137; used for food, 245

_Panulirus_, 241

_Paracyamus_, 55

_Paranaspides_, 264

_Paranephrops_, 177

_Parapagurus_, 124; and Sea-anemones, 213

Parasitism, 208

Parastacidæ, 176

_Parastacus_, 178

Partan, 248

Parthenogenesis, 163; of Cladocera, 166; of Ostracoda, 172

Pea Crab, 217

Pedunculata, 43

_Peltogaster_, 232

Penæidea, 59; fossil, 267

_Penæus_, 59; larvæ, 73; used for food, 247; fossil, 268

Peracarida, 46; development, 78

Pericardium, 17

_Peripatus_, tracheæ of, 204

Peter's stone, 220

_Philomedes_, 38

Phosphorescence. See Luminosity

Photophores of Euphausiacea, 125

Phreatoicidea, 173

_Phronima_, 154

Phronimidæ, eyes of, 154

_Phtisica_, 54

Phyllocarida, 261

_Phyllosoma_, 149; of Spiny Lobster, 72

Phylogeny, 205, 256

Pill Millipede, 203

Pink Shrimp, 137, 245

_Pinnaxodes_, 218

_Pinnotheres_, 217; used for food, 249

_Planes_, 155

Plankton, 139; of fresh water, 160; of lakes, 168, 170; relation to fisheries, 250

_Platyarthrus_, 205

_Platycuma_, 129

_Platymaia_, 130

_Platytelphusa_, 184

Pleuron, 9

Podocopa, 39

_Podocrates_, 269

_Pollicipes_ used for food, 237; fossil, 261

_Polycheles_, 133

_Pontonia_, 218

_Pontoporeia_, 181

Porcelain Crab: zoëa of, 70; autotomy, 114; feeding, 115; and Hermit Crabs, 215

_Porcellana_: zoëa of, 70; autotomy, 114; feeding, 116

Porcellanidæ, 60

_Porcellio_, 51; structure and habits, 202; distribution, 206

Portunidæ: swimming, 90; sand-burrowing, 99; used for food, 249

Potamobiidæ, 176

Potamobius, 174

_Potamon_, 180; young of, 78

_Præanaspides_, 265

Prawns, 58; luminosity of, 127; of deep sea, 136; of fresh water, 174, 179; of Tanganyika, 183; blind, in caves, 185; in Sponges, 210; Isopods parasitic on, 221; Common, 245; used for food, 245; deep-water, 247; fossil, 268

Prosoponidæ, 135, 269

Protandrous hermaphroditism, 221

Protective resemblance, 108

_Protocarcinus_, 269

_Protocaris_, 260

Protopodite, 10

Protozoëa of _Penæus_, 75

_Psathyrocaris_, 130

_Pseudothelphusa_, 193

Pseudo-tracheæ, 202

Pygidium, 259

_Pygocephalus_, 263

_Pylocheles_, 94

Pylochelidæ of deep sea, 136

Recapitulation, theory of, 86

Red-clawed Crayfish, 242

Regeneration in Lobster, 30

Relict faunas, 182

_Remipes_, 102

Reproduction of Cladocera, 166; of _Leptodora_, 169; of Cymothoinæ, 220

Reptantia, 59

Respiration in sand-burrowing Crabs, 99; in amphibious Crabs, 106; in Land Crabs, 193; in _Coenobita_, 195; in _Birgus_, 196; in Land Isopods, 201, 202, 203

Resting eggs of Cladocera, 166; of Copepoda, 170

Resting stage of Copepoda, 171

Reversal of asymmetry in Lobster, 30

Rhizocephala, 43; larvæ, 84; structure and development, 231

River Crabs: young of, 78; habits and distribution, 180; development of, 193

River Prawns, 179; used for food, 248

Robber Crab, 61, 94; habits and structure, 195; breeding, 199

Robertson, David, on habits of Crabs, 97

Rock Lobster. See Spiny Lobster

Rostrum of Lobster, 6

_Sacculina_, 231

Salt lakes, Branchiopoda of, 165

Sand-burrowing Crustacea, 97

Sand-hoppers, 52; habits, 107, 189

_Sapphirina_, 150

Sargasso Sea, 155

Scampo, 240

_Scapellum_, fossil, 261

Scaphognathite, 19

Schizopod Stage of Lobster, 71; of _Penæus_, 75

_Scylla_, 249

Scyllaridæ, fossil, 269

Scyllaridea, 59; Phyllosoma larvæ, 149; fossil, 268

_Scyllarus_, fossil, 269

Sea-slater, 200

Sea-anemones: and Hermit Crabs, 213; carried by Crab, 215

Sea-crawfish. See Spiny Lobster

Sea-urchin, Crab living in, 218

Sedentary Crustacea, 114

Self-mutilation in Lobster, 30

Senses of Lobster, 25

_Sergestes_, zoëa of, 75, 148

Serial homology, 10

_Sesarma_, habits, 180, 189

Sessile Barnacles, 43

Sexes of Lobster, 26

Sexual characters of Crabs infected with _Sacculina_, 235

Sharks, Barnacle parasitic on, 235

Shore Crab, 64; larval stages, 68; habits, 107, 188; infested by _Sacculina_, 231; used for food, 249

Shrimps, 58; fresh-water, 53, 172; Common, habits of, 97; protective resemblance, 108; living with Mollusc, 218; fishery, 244. See also Brown Shrimp, Pink Shrimp, etc.

Sight, sense of, in Lobster, 21

Skeleton Shrimps, 109

Slaters, 51; Sea-, 200

Sloane, H., on Gulf-weed Crab, 155

Smell, sense of, in Lobster, 24

Smith, G.: on terrestrial Amphipoda, 189; on development of _Sacculina_, 233

Smith, S. I., on habits of _Ocypode_, 105

Somites of Lobster, 6, 8

Southern Crayfishes, 176

Spencer and Hall on Australian Branchiopoda, 161, 163

Sperm-receptacle of Lobster, 27

Spider Crabs, 64; masking habits, 96, 215; deep-sea, 128

Spiny Lobster, 59; larva of, 72; fishery, 240

_Spirontocaris_, Isopod parasitic on, 221

Sponge Crab, 95

Sponges, Crustacea in, 210

_Spongicola_, 210

_Squilla_, 64; larva of, 80; fossil, 266

Stalked Barnacles, 43

Statocyst of Lobster, 24; of Mysidacea, 47

Statolith, 47

Stebbing, T. R. R.: on Land Crabs, 190; on habits of _Cirolana_, 219

Steinkrebs, 242

Stenopidea, 59; fossil, 267

_Stenorhynchus_, 97

Sternum, 9

Stevenson, R., on the Gribble, 254

Stomach of Lobster, 16

Stone Crab, 61, 94

Stomatopoda, 64; larvæ, 80; habits, 104; fossil, 266

Stridulating organ of _Ocypode_, 105

Subterranean Crustacea, 184

Swimmerets of Lobster, 6, 10

Swimming Crabs, 90; sand-burrowing, 99; used for food, 249

Symbiosis, 207

Syncarida, 45, 181; fossil, 264

Tail-fan of Lobster, 6

Talitridæ, 107

_Talitrus_: habits, 107; terrestrial Species, 189

Tanaidacea, 50

Tanganyika, Lake, Crustacea of, 183

Taste, sense of, in Lobster, 25

_Telphusa_, 180

Telson of Lobster, 6

Tergum, 9

Testis of Lobster, 27

Thalassinidea, 61; habits, 103

_Thaumastocheles_, 130, 132

Thompson, J. Vaughan: discovery of metamorphoses of Crustacea, 67; on larvæ of Cirripedia, 83; on development of _Sacculina_, 232

Thoracica, 43

Thorax of Lobster, 7

Thread-worms, 252

Touch, sense of, in Lobster, 22

Tracheæ, 204

Tracheæ, pseudo-, 202

Trapeziidæ, 211

_Triarthrus_, 258

Trilobites, structure and history, 258

_Tubicinella_, 209

_Turrilepas_, 261

Turtles: Barnacles on, 209; Gulf-weed Crab on, 209

Underground Crustacea, 184

Uropods of Lobster, 6

Venus's Flower-basket, Crustacea in, 210

Water-fleas, 37, 165

Weismann on parthenogenesis of _Cypris_, 172

Well Shrimp, 184

Westwood, J. O., on development of Land Crabs, 192

Whales, Barnacles on, 209

Whale-food, 138

Whale-lice, 56; habits, 224

White-clawed Crayfish, 242

Willey, A., on breeding of Robber Crab, 199

Williamson, H. C., on habits of Lobster, 25

Wood-boring Crustacea, 253

Woodlice, 51; development of, 79; habits and structure, 199; distribution of, 206; destructive in gardens, 253

Worms: and Hermit Crabs, 215; Copepoda parasitic in, 230

Zoëa of Shore Crab, 69; of Caridea, 73; of Porcelain Crab, 70; of _Munida_, 71; of _Penæus_, 75; of _Sergestes_, 75, 148; of Robber Crab, 199

PRINTED BY BILLING AND SONS, LTD. GUILDFORD

* * * * *

Transcriber's note:

In general every effort has been made to replicate the original text as faithfully as possible, including some instances of non-standard spelling and punctuation. Certain animal names (notably, "Lobster", "Crab") have occasionally been changed from lowercase to capitalized when the pattern of capitalization used by the author has permitted the transcriber to judge that the omission of such capitalization was likely to be typographical in nature and not intentional. The hyphenation is occasionally variable; this has not been altered. A few obvious punctuation errors have been corrected, as well as the following apparently typographical errors:

p. ix (List of Illus.) "8. _Diastylis goodsiri_...," 8 changed to 18 p. xiv (List of Illus.) Plate II page ref., changed from 63 to 36 p. xv (List of Illus.) Plate XXI caption, Palamon changed to Palæmon p. xvi (List of Illus.) Plate XXVII caption, "THE COCO NUT CRAB, Birgus latro," Coco nut changed to Coconut p. 78 Fig 31 caption, "The adult of an allied species is figured on Plate XXV," XXV changed to XXIII p. 165 "Daphnia pulex and other speces," speces changed to species p. 169 "the addomen, however, is drawn" addomen changed to abdomen p. 196 Plate XXVII caption, "THE COCO-NUT CRAB, Birgus latro," COCO-NUT changed to COCONUT p. 208 Plate labeled XXVII (Group of Barnacles...) changed to XXVIII p. 214 "a fleshy mass formed by a colony of Sea-amenones," amenones changed to anemones p. 215 "woud be of little use by themselves," woud changed to would p. 288 (index) missing italics placed on "Sapphirina" p. 289 (index) tergum page reference 8 changed to 9

Some illustrations have been moved from their original locations to paragraph breaks, so as to be nearer to their corresponding text, and for ease of document navigation. Missing page numbers correspond to pages not numbered in the original document. References to scale in illustration captions are those of the original publication, and therefore do not correspond to the scale of the images in the HTML version of this ebook.

End of Project Gutenberg's The Life of Crustacea, by William Thomas Calman