CHAPTER XI.

THE COCKROACH OF THE PAST.

By S. H. SCUDDER, of the U.S. Geological Survey.

_SPECIAL REFERENCES._

BERENDT, G. C. Mémoire pour servir à l’histoire des Blattes antédiluviennes (Ann. Soc. Entom., France, V.). Paris, 1836. 8vo.

BRODIE, P. B. A History of the Fossil Insects in the Secondary Rocks of England. London, 1845. 8vo.

GEINITZ, F. E. Die Blattinen aus der unteren Dyas von Weissig (Nova Acta. Acad. Leop.-Carol., XLI.). Halle, 1880. 4to.

GERMAR, E. F., und BERENDT, G. C. Die im Bernstein befindlichen Hemipteren und Orthopteren der Vorwelt. Berlin, 1856. Fol.

GOLDENBERG, F. Zur Kenntniss der Fossilen Insekten in der Steinkohlenformation (Neues Jahrb. Miner). Stuttgart, 1869. 8vo.

---- Fauna Saræpontana Fossilis. Heft 1–2, Saarbrücken, 1873, 1877. 4to.

HEER, O. Ueber die fossilen Kakerlaken (Viertelj. Naturf. Ges., Zürich, IX.). Zürich, 1864. 8vo.

KLIVER, M. Ueber einige Blattarien ... aus der Saarbrücker Steinkohlenformation (Palæontogr. XXIX.). Cassel, 1883. 4to.

KUSTA, J. Ueber enige neue Böhmische Blattinen (Sitzungsb. böhm. Ges. Wissensch, 1883). Prag. 8vo.

SCUDDER, S. H. Palæozoic Cockroaches (Mem. Bost. Soc. Nat. Hist., III.). Boston, 1879. 4to.

---- The Species of Mylacris (_Ibid_). Boston, 1884. 4to.

---- A Review of Mesozoic Cockroaches (_Ibid_). Boston, 1886. 4to.

---- Triassic Insects from the Rocky Mountains (Amer. Journ. Sc. Arts[3], XXVIII.). New Haven, 1884. 8vo.

---- Systematische Uebersicht der fossilen Myriopoden, Arachnoideen und Insekten (Zittel, Handb. Palæont. I. Abth., Bd. II.). München, 1885. 8vo.

WESTWOOD, J. O. Contributions to Fossil Entomology (Quart. Journ. Geol. Soc., Lond., X.). London, 1854. 8vo.

Like all useful scavengers, the Cockroach is looked upon nowadays as an unmitigated pest. It has, however, a certain right to our regard, for it comes of a venerable antiquity. Indeed, palæontologically considered, no Insect is so interesting as the Cockroach. Of no other type of Insects can it be said that it occurs at every horizon where Insects have been found in any numbers; in no group whatever can the changes wrought by time be so carefully and completely studied as here; none other has furnished more important evidence concerning the phylogeny of Insects. Even the oldest known air-breathing animal has been claimed (though I think erroneously) as a Cockroach; yet, however that may be, it is certain that in the most ancient deposits which have yielded any abundance of Insect remains, the Coal Measures, they so far outnumber all other types of Insects, that this period, as far as its hexapodal fauna is concerned, may fairly be called the _Age of Cockroaches_. And though the subsequent periods show an ever-diminishing percentage of this family when compared with the total synchronous Insect fauna, yet the existing species are counted by hundreds, and the fecundity of some, attested by every housewife, may be looked upon as a sufficient explanation of the persistence of this antique type. The Cockroach is, therefore, a very aristocrat among Insects.

Our knowledge of its past is derived almost entirely from its wings; perhaps because these organs are the farthest removed from the nourishing fluids of the body, which on death become one of the agents, or at least the media, of putrefaction and consequent obliteration. At all events, whatever the cause, these chitinous membranes, with their network of supporting rods, and even not infrequently with the minutest reticulation of the membrane itself, are preserved with extraordinary fidelity, and in such abundance that, by comparison with similar parts in existing forms, we may reach some general conclusions concerning the life of the past of no little interest.

The first thing that would strike an observer, looking at the ancient Cockroaches, would be their _general_ resemblance to the living. Excepting for their usually larger size,[194] were we to have the oldest known Cockroaches in our kitchens to-day, the householder would take no special note of them--unless, indeed, the transparency of their wings (shortly to be mentioned) were to give them a somewhat peculiar aspect. There would be the same rounded pronotal shield, the same overlapping wings, coursed by branching veins, the same smooth curves and oval flattened form of the whole creature, and doubtless also the same scurrying movements. Indeed, some accurate observers--so, I suppose, we must call them--have failed to take note of some important and very general distinctions between the living and the dead. Thus Gerstaecker, in a work begun twenty years ago, and not yet finished, said, near its beginning,[195] “Not a single species of Insect has yet been found in the Carboniferous rocks which does not fall, on closer examination (_mit voller Evidenz_), not only in an existing order, but even almost completely in the same family as some living form, and only presents striking distinctions when compared with the species themselves.” He further specifies the Cockroaches described from the Coal Measures, by Germar and Goldenberg, as agreeing in every distinguishing family characteristic with those of the present day.

[194] Yet none were so large as our largest living forms; their average size was very nearly that of _Periplaneta americana_.

[195] Die Klassen und Ordnungen der Arthropoden. Leipzig, 8vo, p. 292.

In one sense, indeed, this is true. We separate the living Cockroaches from other kinds of Orthoptera as a “family” group, and “Cockroaches” have existed since the Coal Measures at least; yet the structure of every one of the older types is really so peculiar that none of them can be brought within the limits of the family as it now exists. We recognise ours, indeed, as the direct descendants of the ancient forms, but so changed in structure as to form a distinct group. A parallel case is found in the Walking-sticks, and is even more obvious. The recent researches of M. Charles Brongniart have brought to view a whole series of forms in Carboniferous times, which are manifestly the progenitors of living Walking-sticks, with their remarkably long and slender stick-like body, attenuated legs, and peculiar appendages at the tip of the abdomen. Existing forms are either wingless or else have opaque elytron-like front wings, and very ample, gauzy, fan-like hind wings; while the Carboniferous species are furnished with four membranous wings, almost precisely alike, and so utterly different from those of existing types that, before the discovery of the bodies, these wings were universally classed as the wings of Neuropterous Insects (sensu Linneano). Thus Gerstaecker, in the very place already quoted, says of these same wings, known under the generic name _Dictyoneura_, that they show at least a very close relationship to the _Ephemeridæ_ of to-day.

One principal difference here alluded to--the exact resemblance, except in minor details, of the front and hind wings, and, as consequent therewith, _equal diaphaneity in both_--is found indeed in all palæozoic insects, with exceedingly few exceptions;[196] it is one of their most characteristic and pervading peculiarities. It marks one phase of the movement in all life from homogeneity to heterogeneity--from the uniform to the diverse. In the Cockroaches of to-day a few are found in which the tegmina are nearly as diaphanous as the hind wings; but in the great mass the texture of the tegmina, as in Orthoptera generally (excepting most Gryllides), is decidedly coriaceous; and in some, _e.g._, _Phoraspis_, the veins are nearly obliterated in the thickness and opacity of the membrane, so as to resemble many Coleopterous elytra.

[196] A few elytra of Coleoptera are recently announced from the Silesian “culm.”

Three principal differences have been noticed between the ancient and modern forms of Cockroaches. Doubtless others could be found were we able to compare the structure of all parts of the body; and perhaps future research and more happy discovery may yet bring them to light; at present, however, we are compelled to restrict our comparisons to the wings alone.

First, we have to remark the similarity of the front and hind wings in the ancient types: a similarity which extends to their general form (the extended anal area of the hind wings in modern types being as yet only slightly differentiated); their nearly equal size (a corollary, to a certain extent, of the last); the general course of their neuration (true, in a limited sense only, of modern types); and the complete transparency of the front as well as of the hind wing.

Second, the same number of principal veins is developed in the front and hind wings of ancient Cockroaches; while in the front wings of modern types two or more of the veins are blended, so as to reduce the number of the principal stems below the normal, the hind wing at the same time retaining its original simplicity. These principal veins are six, counting the marginal vein, which here merely thickens the anterior border, as one; to use the terminology of Heer, and starting from the anterior margin, they are the _marginal_, _mediastinal_, _scapular_, _externomedian_, _internomedian_, and _anal_. The general disposition of these veins is as follows:--The mediastinal and scapular veins, with their branches, which are superior (_i.e._, part from the main vein on the upper or anterior side), terminate upon the anterior margin. The internomedian and anal take the opposite course, and their branches are inferior, or, at least, directed toward the inner margin; while the externomedian, interposed between these two sets, terminates at the tip of the wing, and branches indifferently on either side.

Now these veins are all present in both front and hind wings of palæozoic Cockroaches, and also in the hind wings of existing species; but in the front wings or tegmina of the latter the number is never complete, the externomedian vein being always amalgamated either with the scapular, or with the internomedian, and the mediastinal frequently blended with the scapular vein.

The hind wings are thus shown to be conservative elements of structure, since they have preserved from the highest antiquity both their transparency and their normal number of veins. They have retained the use to which they were first put, and the changes that have come about, such as the wider expansion of the anal area, have been in fuller development of the same purpose; while the front wings, in virtue of their position in repose, have become more and more protectors of the hind wings, and have gradually lost, in part, if not entirely, their original use. The hind wings of existing Insects, thus protected, have given less play to selective action, and have become to some degree interpreters for us of the more complicated structure, the more modernised anatomy, the more varied organisation of the front wing.

A third distinction between palæozoic and modern Cockroaches is found in the veinlets of the anal area. These, unlike the branches of the other veins, do not part from the main anal vein at various points along its course, but form a series of semi-independent veinlets, and in palæozoic Cockroaches take the same general course as the main anal vein, or “anal furrow” (the curved, deeply sunken vein that marks off the anal area from the rest of the front wing, both in ancient and modern Cockroaches), and terminate at sub-equidistant intervals upon the inner margin; while in modern Cockroaches these veins either run sub-parallel to the inner margin and terminate on the descending portion of the anal furrow, or they form a fusiform bundle and terminate in proximity to one another and to the tip of the anal furrow.

These differences, which were mentioned by Germar and Goldenberg, and their universality pointed out in my memoir on Palæozoic Cockroaches,[197] seem to warrant our separating the older forms from the modern as a family group, under the name of _Palæoblattariæ_; this family has been thus characterised:--

[197] Memoirs Bost. Soc. Nat. Hist., III., 23 seq. (1880).

Fore wings diaphanous, generally reticulated, and nearly symmetrical on either side of a median line. Externomedian vein completely developed, forking in the outer half of the wing, its branches generally occupying the apical margin; internomedian area broad at base (beyond the anal area), rapidly tapering apically, and filled with oblique mostly parallel veins, having nearly the same direction as the anal veinlets, which, like them, strike the inner margin.

About eighty palæozoic species have been published up to the present time, and have been grouped in two sub-families and thirteen genera. Besides these, Brongniart has not yet given any hint of how many have been found at Commentry, a French locality which may be expected to increase the number largely, and about twenty undescribed species are known to me from the American Carboniferous rocks.

The two tribes or sub-families differ in the structure of the mediastinal vein; in one type (_Blattinariæ_) the branches part from the main stem as in the other veins, at varying distances along its course (see the figure of _Etoblattina_); in the other (_Mylacridæ_) they spread like unequal rays of a fan from the very base of the wing (see the figure of _Mylacris_). What is curious is that the latter type has been found only in the New World, while the former is common to Europe and America. The latter appears to be the more archaic type, since it is probable that the primeval Insect wing was broad at the base, as is the general rule in palæozoic wings, and had the veins somewhat symmetrically disposed on either side of a middle line; in this case the mediastinal and anal areas would be somewhat similar and more or less triangular in form, and the space they occupied would be most readily filled by radiating veins; such a condition of things, which we find in the _Mylacridæ_, would naturally precede one in which the mediastinal vein, to strengthen the part of the wing most liable to strain, should, as in the _Blattinariæ_, follow the basal curve of the costal margin, and throw its branches off at intervals toward the border, much after the fashion of the mediastinal vein.

This view of the relative antiquity of the two tribes of _Palæoblattariæ_ is supported by the fact that while in both of them the internomedian branches show a tendency to repeat the general course of the anal nervules, as in the corresponding veins of the costal region, this tendency is lost in modern types; and among those ancient _Blattinariæ_, which are esteemed highest in the series, there is a marked tendency toward a loss of this repetition of the style of branching of the mediastinal and anal offshoots by the scapular and internomedian respectively.

A certain amount of geological evidence may also be claimed in support of this view. A survey of the species of the two groups found up to the present time in America, published and unpublished, shows that all the _Mylacridæ_ are found below the Upper Carboniferous, while more than half the _Blattinariæ_ are found in or above it. This results largely from a recent and as yet unpublished discovery of _Blattinariæ_ in the Upper Coal Measures of Ohio and West Virginia, which in their general features are much nearer than previously discovered American Cockroaches to the European _Blattinariæ_, the latter of which come generally from Upper Carboniferous beds. The _Mylacridæ_ have therefore been found in America in strata generally regarded as older than those which in Europe have yielded Cockroaches, and this gives a sufficient explanation why no _Mylacridæ_ have yet been found in the Old World. In America one is mostly dealing with absolutely older forms, and they naturally give that continent a more old-fashioned look, when we regard the Carboniferous fauna as a whole. As already stated, a wing from the French Silurian (_Palæoblattina Douvillei_ Brongn.) has been claimed as a Cockroach, but without good reason, and to see a real old Cockroach one must look to America.

Up to this point we have contrasted the palæozoic Cockroaches with the existing forms only, and finding such important distinctions between them, we naturally turn with some curiosity to the intermediate mesozoic and tertiary formations.

Now, not only are the mesozoic species as numerous (actually, but not relatively) as the palæozoic, but a recent discovery of a Triassic fauna of considerable extent, in the elevated parks of Colorado, presents us with a series of intermediate forms between those peculiar to the Coal Measures and those characteristic of the later mesozoic rocks. Excluding, however, for a moment this Triassic fauna, we may say of the later mesozoic species that they are _Neoblattariæ_, not _Palæoblattariæ_, though they still show some lingering characteristics of their ancestry. Thus the front wings are in general of a less dense texture than in modern times, but without the perfect diaphaneity of the palæozoic species; in some the anal veins fall in true palæoblattarian fashion on the inner margin, while in others which cannot be dissociated generically from them, the anal veins are disposed as in modern types. But in all there is a loss of one of the principal veins, or rather an amalgamation of two or more--a characteristic of more fundamental character. As a general rule, moreover, to which we shall again advert, the mass of the species are of small size, in very striking contrast to the older types.

To return now to the Triassic deposits of Colorado, we recognize here an assemblage of forms of a strictly intermediate character. Here are _Palæoblattariæ_ and _Neoblattariæ_, side by side. The larger proportion are _Palæoblattariæ_, but all of them are specifically, and most of them generically, distinct from palæozoic species, and all rank high among _Blattinariæ_; still further, the species are all of moderate size, their general average being but little above that of mesozoic Cockroaches, and only a little more than half that of palæozoic types. The _Neoblattariæ_ of this Triassic deposit are still smaller, being actually smaller than the average mesozoic Cockroach, and one or two of them, of the genus _Neorthroblattina_ (see figure of _N. Lakesii_), have marked affinity to one of the genera of Palæoblattariæ (_Poroblattina_) peculiar to the same beds, differing mainly in the union or separation of the mediastinal and scapular veins; while others, as _Scutinoblattina_, have a _Phoraspis_-like aspect and density of membrane. This novel assemblage of species bridges over the distinctions between the _Palæoblattariæ_ and _Neoblattariæ_. We find, first, forms in which the front wings are diaphanous, with distinct mediastinal and scapular veins, and the anal veinlets run to the border of the wing (_Spiloblattina_, _Poroblattina_); next, those having a little opacity of the front wings, with blended mediastinal and scapular, and the anal veins as before (some species of _Neorthroblattina_); then those with still greater opacity, with the same structural features (other species of _Neorthroblattina_); next, those having a coriaceous or leathery structure, blended mediastinal and scapular, and anal veins falling on the inner margin (some species of _Scutinoblattina_); and, finally, similarly thickened wings with blended mediastinal and scapular, and anal veins impinging on the anal furrow (other species of _Scutinoblattina_).

It is not alone, however, by the union of the mediastinal and scapular stems that the reduction of the veins in the wings of later Cockroaches has come about; for in many mesozoic types the externomedian vein is blended with one of its neighbours, while in others not only are the mediastinal and scapular united, but at the same time the externomedian and internomedian.

As regards the other structural distinction between the _Palæoblattariæ and Neoblattariæ_--the course of the anal nervules--there is much diversity, and very imperfect knowledge, since this very portion of the wing is not infrequently lost, a fracture most readily occurring at the anal furrow. In most of the mesozoic genera, the anal nervules, as far as known, strike the margin; but the larger portion of these show a decided tendency to trend toward the tip of the anal furrow, as in many modern forms. This feature can hardly be considered as firmly established in mesozoic times, and the same genus, as _Scutinoblattina_, may contain species which differ in this respect.

A further peculiarity of mesozoic Cockroaches, already alluded to, is their generally small size. The average length of the front wing of palæozoic Cockroaches has been estimated to be 26 mm., that of the Triassic _Palæoblattariæ_ is about 16 mm., while that of the mesozoic _Neoblattariæ_ is 12·5 mm. One exception to this small size must be noted in the species from the Jura of Solenhofen, all of which were large and some gigantic, one wing reaching the length of 60 mm., or about the size of our largest tropical _Blaberæ_. If we omit these exceptional forms, the average length of the wing of the mesozoic Cockroach would be scarcely more than 11 mm. Now an average of the 243 species of which the measurements are given in Brunner’s Système des Blattaires (1865), gives the length of the front wing of living Cockroaches as a little over 18 mm.; so that the mesozoic Cockroaches were as a rule considerably smaller, the palæozoic Cockroaches much larger, than the living.

Nearly eighty species of mesozoic _Neoblattariæ_ are known, and they are divided into thirteen genera,[198] one of which, _Mesoblattina_ (see figure of _M. Brodiei_), contains upwards of twenty species, mainly from the Lias and Oolites of England. The Upper Oolite has proved the most prolific, considerably more than half the species having been found in the English Purbecks, while nearly a fourth occur in the Lias of England, Switzerland, and Germany. Many of the English species have been figured in Brodie’s Fossil Insects of the Secondary Rocks of England, in Westwood’s paper on Fossil Insects in the tenth volume of the Quarterly Journal of the Geological Society, and in the memoir alluded to above. No species has yet been found in rocks of different geological horizons, and the genera of the Trias are peculiar to it. So, too, are some of the genera of the Oolite, but all of the Liassic genera occur also in the Oolite.

[198] See a paper on mesozoic Cockroaches now printing in the Memoirs Bost. Soc. Nat. Hist., Vol. III., p. 439 seq.

Among these mesozoic Cockroaches are some of very peculiar aspect; one, _Blattidium_ (see figure of _B. Simyrus_), found only in the lower Purbecks, has ribbon-shaped wings with parallel sides, longitudinal neuration, and anal nervures with a course at right angles to their usual direction; another, _Pterinoblattina_ (see figure of _P. intermixta_), geologically widespread, is very broad, more or less triangular, and has an exceedingly fine and delicate neuration, so arranged as to resemble the barbs of a feather.

A comparison of the neuration of the tegmina of mesozoic and recent Cockroaches, to determine as far as possible the immediate relations of the former to existing types, gives as yet little satisfaction. The prolific genera, _Mesoblattina_ and _Rithma_, may be said to bear considerable resemblance to the _Phyllodromidæ_, and the peculiar neuration of _Elisama_ is in part repeated in the _Panchloridæ_, as well as in some _Phyllodromidæ_ and _Epilampridæ_. _Scutinoblattina_ also reminds one in certain features of some _Epilampridæ_, like _Phoraspis_. The other genera appear to have no special relations to any existing type. As a whole, it would appear as if the _Blattariæ spinosæ_ approached closer to the mesozoic forms than do the _Blattariæ muticæ_.

As to the tertiary Cockroaches we know very little, exceedingly few having been preserved, even in amber--that wonderful treasury of fossil Insects. Here first we come across apterous forms, _Polyzosteria_ having been recognised in Prussian amber,[199] together with winged species, which seem to be _Phyllodromidæ_; these are the only _Blattariæ spinosæ_ known from the Tertiaries. Of the other group, we have _Zetobora_, one of the _Panchloridæ_, and _Paralatindia_, one of the _Corydidæ_, from American rocks, and _Heterogamia_ and _Homœogamia_, one from Parschlug in Steiermark, the other from Florissant in Colorado, belonging to the sub-family _Heterogamidæ_. Others are mentioned, generally under the wide generic term _Blatta_, from Oeningen, Eisleben, Rott, and even from Spitzbergen and Greenland; but little more than their names are known to us. _Paralatindia_, from the Green River beds of Wyoming, U.S., is the only tertiary Cockroach yet referred to an extinct genus; but close attention has not yet been paid even to the few tertiary Cockroaches which we know. There is no reason to suppose that they will be found to differ more from the existing types than is generally the case with other Insects. The more we learn of cænozoic Insects, the more truly do we find that the early Tertiary period was in truth the dawn of the present, the distinction between the faunas of these remotely separated times (though not to be compared in character) being scarcely greater than is found to-day between the Insects of the temperate and torrid zones.

[199] The wingless creature from the Carboniferous deposits of Saarbrücken, described by Goldenberg as a Cockroach, under the name of _Polyzosterites granosus_, appears to be a Crustacean.

We began this review with the statement that no Insect was so important palæontologically as the Cockroach. This would more clearly appear had we space to pass in review the geological history of all the Insect tribes; for then it could be shown that it was only in the passage from palæozoic to mesozoic times that the great ordinal groups of Insects were differentiated, and that the Triassic period therefore becomes the expectant ground of the student of fossil Insects. Up to the present time we do not know half a dozen Insects besides Cockroaches from these rocks. Yet, notwithstanding this advantage on the part of the Cockroaches, how meagre is the history, how striking the “imperfection of the geological record” concerning them, the following tabulation of the fossil species by their genera will show.

It here appears that there are about 80 species known from the palæozoic rocks, two or three more than that from the mesozoic, and only nine from the cænozoic! When we call to mind that half the palæozoic Insects were Cockroaches, and that seven or eight hundred species exist to-day, what shall we say of the paltry dozen[200] from the rich tertiaries? Shall we claim that these figures represent their true numerical proportion to their numbers in the more distant past? Then, indeed, must the palæozoic period have been the Age of Cockroaches; for all research into the past shows that a type once losing ground continues to lose it, and does not again regain its strength. The Cockroaches of to-day are no longer, as once, a dominant group; they are but a fragment of the world’s Insect-hosts; yet even now the species are numbered by hundreds. If this be a waning type, what must its numbers have been in the far-off time, when the warm moisture which they still love was the prevailing climatic feature of the world; and how few of that vast horde have been preserved to us! The housekeeper will thank God and take courage.

[200] This includes all possible forms; our table shows but nine.

GEOLOGICAL DISTRIBUTION OF FOSSIL COCKROACHES.

Figures in _italics_ represent the number of American species; in roman, of European.

+---------------------+-------------------+----+----+----+----+----+----+ | |Carboniferous.| | | | U | O | M | | | | L | M | U | P | T | L | p | l | i | T | | | o | i | p | e | r | i | p | i | o | O | | | w | d | p | r | i | a | e | g | c | T | | | e | d | e | m | a | s. | r | o | e | A | | | r. | l | r. | i | s. | | J | c | n | L | | | | e. | | a | | | u | e | e. | S. | | | | | | n. | | | r | n | | | | | | | | | | | a. | e. | | | +---------------------+----+----+----+----+----+----+----+----+----+----+ |PALÆOBLATTARIÆ. | | | | | | | | | | | | _Mylacridæ_-- | | | | | | | | | | | | Mylacris |_10_| .. | .. | .. | .. | .. | .. | .. | .. | 10 | | Promylacris | _1_| .. | .. | .. | .. | .. | .. | .. | .. | 1 | | Paromylacris | _1_| .. | .. | .. | .. | .. | .. | .. | .. | 1 | | Lithomylacris | _2_| _2_| .. | .. | .. | .. | .. | .. | .. | 4 | | Necymylacris | _2_| .. | .. | .. | .. | .. | .. | .. | .. | 2 | | _Blattinariæ_-- | | | | | | | | | | | | Etoblattina | _1_| 1 |15+ | 3+ | | .. | .. | .. | .. |} | | | .. | .. | _6_| _1_| _1_| .. | .. | .. | .. |}28 | | Spiloblattina | .. | .. | .. | .. | _4_| .. | .. | .. | .. | 4 | | Archimylacris | _3_| .. | .. | .. | .. | .. | .. | .. | .. | 3 | | Anthracoblattina | .. | 2 | 6 | 4 | _1_| .. | .. | .. | .. | 13 | | Gerablattina | _1_| 1 | 10 | .. | .. | .. | .. | .. | .. | 12 | | Hermatoblattina | .. | .. | 1 | 1 | .. | .. | .. | .. | .. | 2 | | Progonoblattina | .. | .. | 2 | .. | .. | .. | .. | .. | .. | 2 | | Oryctoblattina | _1_| .. | 1 | 1 | .. | .. | .. | .. | .. | 3 | | Petrablattina | _1_| .. | .. | 1 | _2_| .. | .. | .. | .. | 4 | | Poroblattina | .. | .. | .. | .. | _2_| .. | .. | .. | .. | 2 | | |(23)| (6)|(41)|(11)|(10)| | | | |(91)| |NEOBLATTARIÆ. | | | | | | | | | | | |N t | | | | | | | | | | | |o o {Ctenoblattina | .. | .. | .. | .. | .. | 1 | 2 | .. | .. | 3 | |t {Neorthroblattina| .. | .. | .. | .. | _4_| .. | .. | .. | .. | 4 | | s {Rithma | .. | .. | .. | .. | .. | 2 | 10 | .. | .. | 12 | |y u {Mesoblattina | .. | .. | .. | .. | .. | 7 | 15 | .. | .. | 22 | |e b {Elisama | .. | .. | .. | .. | .. | 1 | 5 | .. | .. | 6 | |t - {Pterinoblattina | .. | .. | .. | .. | .. | 3 | 6 | .. | .. | 9 | | f {Blattidium | .. | .. | .. | .. | .. | .. | 2 | .. | .. | 2 | |r a {Nannoblattina | .. | .. | .. | .. | .. | .. | 3 | .. | .. | 3 | |e m {Dipluroblattina | .. | .. | .. | .. | .. | .. | 1 | .. | .. | 1 | |f i {Diechoblattina | .. | .. | .. | .. | .. | .. | 2 | .. | .. | 2 | |e l {Scutinoblattina | .. | .. | .. | .. | _3_| .. | .. | .. | .. | 3 | |r i {Legnophora | .. | .. | .. | .. | 1 | .. | .. | .. | .. | 1 | |r e {Aporoblattina | .. | .. | .. | .. | .. | 3 | 6 | .. | .. | 9 | |e s | | | | | (8)|(17)|(52)| | |(77)| |d . | | | | | | | | | | | | | | | | | | | | | | | | _Phyllodromidæ_-- | | | | | | | | | | | | “Blatta” | .. | .. | .. | .. | .. | .. | .. | 3 | .. | 3 | | _Periplanetidæ_-- | | | | | | | | | | | | Polyzosteria | .. | .. | .. | .. | .. | .. | .. | 2 | .. | 2 | | _Panchloridæ_-- | | | | | | | | | | | | Zetobora | .. | .. | .. | .. | .. | .. | .. | _1_| .. | 1 | | _Corydidæ_-- | | | | | | | | | | | | Paralatindia | .. | .. | .. | .. | .. | .. | .. | _1_| .. | 1 | | _Heterogamidæ_-- | | | | | | | | | | | | Homœogamia | .. | .. | .. | .. | .. | .. | .. | _1_| .. | 1 | | Heterogamia | .. | .. | .. | .. | .. | .. | .. | .. | 1 | 1 | | | | | | | | | | (8)| (1)| (9)| +---------------------+----+----+----+----+----+----+----+----+----+----+ | GRAND TOTALS | 23 | 6 | 41 | 11 | 18 | 17 | 52 | 8 | 1 |177 | +---------------------+----+----+----+----+----+----+----+----+----+----+

Samuel H. Scudder.

APPENDIX.

PARASITES OF THE COCKROACH.

_Spirillum, sp._ [Vibrio]. SCHIZOMYCETES.

Rectum.

_Ref._--Bütschli, Zeits. f. wiss. Zool., Bd. XXI., p. 254 (1871).

_Hygrocrocis intestinalis_, Val. CYANOPHYCEÆ.

Filaments of a very minute Alga abound in the rectum of the Cockroach, where this species is said by Valentin to occur. The intestine of the Crayfish is given as another habitat. Leidy observes that the filaments which he found in the rectum of the Cockroach are inarticulate, and do not agree with Valentin’s description of the species.

_Ref._--Valentin, Repert. f. Anat. u. Phys., Bd. I., p. 110 (1836); Robin, Végét. qui croissent sur l’Homme, p. 82 (1847); Leidy, Smithsonian Contr., Vol. V., p. 41 (1853); Bütschli, Zeits. f. wiss. Zool., Bd. XXI., p. 254 (1871).

_Endamœba (Amœba) Blattæ_, Bütschli. RHIZOPODA.

Rectum.

_Ref._--Siebold, Naturg. wirbelloser Thiere (1839) _fide_ Stein; Stein, Organismus d. Infusions-thiere, Bd. II., p. 345 (1867); Bütschli, Zeits. f. wiss. Zool., Bd. XXX., p. 273, pl. xv. (1878); Leidy, Proc. Acad. N. S. Phil., Oct. 7th, 1879, and Freshwater Rhizopods of N. America, p. 300 (1879).

_Gregarina (Clepsidrina) Blattarum_, Sieb. GREGARINIDA.

Encysted in chylific stomach and gizzard; free in large intestine.

_Ref._--Siebold, Naturg. wirbelloser Thiere, pp. 56, 71 (1839); Stein, Müll. Arch., 1848, p. 182, pl. ix., figs. 38, 39; Leidy, Trans. Amer. Phil. Soc., Vol. X., p. 239 (1852); Bütschli, Zeits. f. wiss. Zool., Bd. XXI., p. 254 (1871), and Bd. XXXV., p. 384 (1881); Schneider, Grégarines des Invertébrés, p. 92, pl. xvii., figs. 11, 12 (1876).

_Nyctotherus ovalis_, Leidy. INFUSORIA.

Small and large intestines.

_Ref._--Leidy, Trans. Amer. Phil. Soc., Vol. X., p. 244, pl. xi. (1852).

_Plagiotoma (Bursaria) blattarum_, Stein. INFUSORIA.

Rectum.

_Ref._--Stein, Sitzb. d. königl. Böhm. Ges., 1860, pp. 49, 50.

_Lophomonas Blattarum_, Stein. INFUSORIA.

Rectum.

_Ref._--Stein (loc. cit.); Bütschli, Zeits. f. wiss. Zool., Bd. XXX., p. 258, plates xiii., xv. (1878).

_L. striata_, Bütschli. INFUSORIA.

Rectum.

_Ref._--Bütschli, Zeits. f. wiss. Zool., Bd. XXX., p. 261, plates xiii., xv. (1878).

_Gordius_, sp. NEMATELMINTHA.

Specimens in the Museum at Hamburg, from Venezuela. Obtained from some species of Cockroach.

_Oxyuris Diesingi_, Ham. NEMATELMINTHA.

Rectum, frequent.

_Ref._--Hammerschmidt, Isis, 1838; Bütschli, Zeits. f. wiss. Zool., Bd. XXI., p. 252, pl. xxi. (1871).

_O. Blattæ orientalis_, Ham. NEMATELMINTHA.

Rectum (much rarer than _O. Diesingi_).

_Ref._--Hammerschmidt (_loc. cit._); Bütschli, Zeits. f. wiss. Zool., Bd. XXI., p. 252, pl. xxii. (1871).

Other species of _Oxyuris_ are said to occur in the same situation,

_e.g._, _O. gracilis_ and _O. appendiculata_ (Leidy, Proc. Acad. N. S. Phil., Oct. 7th, 1879), and _O. macroura_ (Radkewisch, quoted by Van Beneden in Animal Parasites, Engl. trans., p. 248).

_Filaria rhytipleurites._ NEMATELMINTHA.

Encysted in the fat-body of the Cockroach; sexual state in the alimentary canal of the Rat. _Spiroptera obtusa_ is similarly shared by the Meal-worm (larva of _Tenebrio molitor_) and the Mouse.

_Ref._--Galeb, Compt. Rend., July 8th, 1878.

_Acarus_, sp. ARACHNIDA.

Found by Cornelius upon the sexual organs of a male Cockroach.

_Ref._--Cornelius, Beitr. zur nähern Kenntniss von _Periplaneta orientalis_, p. 35, fig. 23 (1853).

_Evania appendigaster_, L. INSECTA (_Hymenoptera_).

A genus of Ichneumons, parasitic upon _Periplaneta_ and _Blatta_.

_Ref._--Westwood, Trans. Ent. Soc., Vol. III., p. 237; Ib., Ser. II., Vol. I., p. 213.

_Symbius Blattarum_, Sund. INSECTA (_Coleoptera_).

The apterous female is parasitic upon _P. americana_ and _B. germanica_.

_Ref._--Sundevall, Isis, 1831.

* * * * *

SENSE OF SMELL IN INSECTS.

Since the printing of the sheets which describe the organs of special sense, we have become acquainted with two experimental researches of recent date, instituted for the purpose of determining whether other organs, besides the antennæ, may be specially concerned with the perception of odours by Insects.

Prof. Graber (Biol. Centralblatt, Bd. V., 1885) has described extensive and elaborate experiments upon various Insects, tending to the conclusion that the palps and the cerci may be sensitive to odours, and that in special cases the palps may be even more sensitive in this respect than the antennæ. Cockroaches, decapitated, but kept alive for some days, were found to perceive odours by means of their cerci. His general conclusion is that Insects have no special sense of smell, but that various parts of the surface of the body are furnished with nerve-endings capable of perceiving strong odours. Prof. Graber’s results are known to us only through the abstract given by Prof. Plateau in the paper next to be mentioned.

Prof. Plateau (Compt. rend. de la Soc. Entom. de Belgique, 1886) relates experiments upon the powers of scent resident in different organs of the Cockroach. Two Cockroaches had their palps (maxillary and labial) removed; two others had the antennæ removed. An evaporating dish, 8 inches in diameter, was then partly filled with fine sand. In the centre of the dish was set a circular box of card, without bottom, 2 inches in diameter, and 1-4/5 inches high. In this box bread moistened with beer, a bait very attractive to Cockroaches, was placed, and renewed daily. The four Cockroaches were allowed to run about in the dish outside the box, and to feed upon the bread at pleasure by climbing over the enclosure. Observations were made late at night for a month, when it was found that, except on the first night, when the Insects ran all over the dish, none of the Cockroaches without antennæ made their way to the food; while twenty-three times one of the Cockroaches without palps, but with antennæ intact, was found to be feeding; in one instance, both were so found.

Plateau observes that a special sense of smell can only be claimed for organs which are able to detect faint and distant odours, and that experiments made with powerful odours close to the body of the Insect may lead to fallacious results. The perception of faint odours cannot be effected by the palps or cerci of the Cockroach, but only by the antennæ.

THE END.

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