part 5, pl. XXIV.
1830 _Ligia hypnorum_ Bosc (2), p. 179. 1833 _Ligidium persoonii_ J. F. Brandt (3), p. 174, pl. IV., figs. 6-7. 1840 _Zia agilis_ Koch (34), part 34, pls. XXII. and XXIII. 1844 _Ligidium personii_ Zaddach (77), p. 17. 1853 _Ligidium personii_ Lereboullet (39), p. 14, pl. I., fig. 1, pl. II., figs. 20-31. 1857 _Ligidium personii_ Kinahan (32), p. 275, pl. XXI., fig. 14, pl. XXII., fig. 9. 1873 _Zia saundersii_ Stebbing (70), p. 286. 1873 _Ligidium agile_ Norman (48), p. 419. 1885 _Ligidium hypnorum_ Budde-Lund (8), p. 254. 1898 _Ligidium hypnorum_ G. O. Sars (59), p. 158, pl. LXXI.
This species, which like the last, is the only British representative of its genus, was added to our fauna in 1873 by the Rev. Thomas R. R. Stebbing (70) who found specimens in the neighbourhood of Copthorne Common, Surrey. Up to the present time, when we are pleased to announce that we discovered it in the spring of 1902 at Warley in Essex, _Ligidium hypnorum_ has not been recorded from any other place in the British Islands.
As the name of the species implies, it lives in wet situations and in its turn connects _Ligia_ with the forms which inhabit drier places. _Ligidium hypnorum_ might be mistaken for _Philoscia muscorum_, but as already pointed out in the generic description, the latter has but a few (three) joints to the flagellum, instead of from ten to thirteen. From _Ligia_, the species under consideration is distinguished by its small size, narrow abdomen, and habitat.
_BRITISH LOCALITIES:--_
_England_: Warley, Essex; (W.M.W.): Copthorne Common, Surrey; (Stebbing, 70).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Sweden; Denmark; Germany; (59): Turkey; (8).
_Family_--TRICHONISCIDÆ.
=Flagellum with less than ten joints; head with lateral lobes; tail appendages partly hidden.=
_Genus_--=TRICHONISCUS= Brandt, 1833 (3), p. 174.
_Abdomen narrow; eyes compound; flagellum, usually with more than three joints._
In _Trichoniscus_ the flagellum may have from seven to four (rarely three) joints. As in _Trichoniscoides_ and _Haplophthalmus_ there are lateral lobes to the head, though these are not very pronounced; the body is also of small size, the abdomen narrow with both divisions of the tail appendages equally so, and almost of the same length though slightly covered by the last segment. The compound eyes distinguish _Trichoniscus_ from the two genera named, and from _Platyarthrus_, while its small size and the character of its tail-parts mark it out from all others.
=Trichoniscus pusillus= Brandt. Plate III.
1833 _Trichoniscus pusillus_ Brandt (3), p. 174, pl. IV., fig. 9. 1838 _Itea riparia_ Koch (34), part 22, pl. XVII. 1844 _Itea lævis_ Zaddach (77), p. 16. 1857 _Philougria celer_ Kinahan (32), p. 281, pl. XXII., figs. 1-4. 1858 _Philougria riparia_ Kinahan (33), pp. 191 and 198, pl. XXIII., fig. 1. 1868 _Philougria riparia_ Bate and Westwood (1), p. 456. 1898 _Trichoniscus pusillus_ Sars (59), p. 161, pl. LXXII., fig. 1.
This tiny species is found commonly amongst the roots of the herbage in very moist places. It presents a horny translucent appearance and is of a reddish brown colour. It runs with considerable speed, and when it is moving, the white irregular lines with which it is beset are not evident. _Trichoniscus pusillus_ is very much like _Trichoniscus vividus_ in colour but the latter species is nearly twice as big and has from five to seven joints to the flagellum, while the former has never more than four. _Trichoniscus roseus_ is also much larger and its bright red colour (which it loses, however, when preserved in alcohol) is another means of distinguishing it from the species under consideration.
Professor Sars in his _Crustacea of Norway_ (p. 162) describes from Christiania, under the name of _Trichoniscus pygmæus_, a still smaller species. As this may possibly be discovered in this country a brief comparison between it and _Trichoniscus pusillus_ may be of value. The former reaches a length of but two millimetres; it is "whitish, semi-pellucid with a few light brown pigmentary ramifications across the segments and a double row of irregular opaque patches along the middle of its back" (p. 163). Its body is covered with minute tubercles and there are only three joints to the flagellum; its movements are by no means rapid.
The body of _Trichoniscus pusillus_ is smooth and polished. It has four joints to the flagellum--Dr. Scharff (63) says three or four--and it moves quickly.
_BRITISH LOCALITIES:--_
_England_: Brightlingsea; Warley; (W.M.W.): Epping Forest; (Bate and Westwood, 1): Hanwell; Southall; Kew Gardens; Langley; Burnham Beeches; Dropmore; Skirmett; Bluebell Hill, Maidstone; (W.M.W.): Chislehurst; Plymouth; Polperro; Looe; (Bate and Westwood, 1): Hertfordshire; Northumberland; Durham; (Norman, 49): Exeter; (Parfitt, 53).
_Scotland_: Edinburgh; (Scott, 68): Cumbrae; (Robertson, 57).
_Ireland_: Connemara; (Norman, 49): Dublin; Wexford; Cork and Kerry; (Percival Wright _teste_ Bate and Westwood, 1): Tyrone; Waterford; Portlaw; Kilkenny; Wicklow; (Kinahan, 33).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Spain; (15): Italy; (19): Norway; Sweden; Denmark; Germany; (59).
_Africa_: Algeria; Tunis; Azores; (24).
_America_: Niagara; North America; (59).
=Trichoniscus vividus=, Koch. PLATE IV. (from a spirit specimen).
1840 _Itea vivida_ Koch (34), part 34, pl. IV. 1858 _Philougria vivida_ Kinahan (33), pp. 197 and 198, pl. XXIII., fig. 2. 1868 _Philougria vivida_ Bate and Westwood (1), Vol. II., pp. 458 and 459, figs.
This species is claret-brown in colour and under a lens it is seen to be marbled with white, indeed in appearance it is much like _Trichoniscus pusillus_ though twice the size. There are important differences between the two species as regards the number of joints to the flagellum. These vary from five to seven in _Trichoniscus vividus_ while in the other, as already pointed out, there are not more than four. The body is practically speaking smooth for it bears only very small tubercles, widely separated. In _Trichoniscus vividus_ the antennæ lack the bristles which characterise those of the other species in the genus. The species under consideration was discovered by Dr. Kinahan in March, 1858, at Portlaw, Co. Waterford and is active even amongst the snow.
_BRITISH LOCALITIES:--_
_Ireland_: Portlaw, Co. Waterford; (Kinahan, 33): Cappagh, Co. Waterford; (Scharff, Irish Nat., Vol. IX., p. 158): Borris, Co. Carlow; (Scharff, 64.)
_FOREIGN DISTRIBUTION:--_
_Europe_: Spain; (12).
=Trichoniscus roseus= Koch. PLATE V.
1838 _Itea rosea_ Koch (34), part 122, pl. XVI. 1858 _Philougria rosea_ Kinahan (33), pp. 197 and 199, pl. XXIII., fig. 3. 1858 _Philougria rosea_ Bate and Westwood (1), p. 460. 1898 _Trichoniscus roseus_ Sars (59), p. 163, pl. LXXIII., fig. 1.
The third British species of _Trichoniscus_ is of a deep pink colour and has a light yellow stripe down the back (in some habitats the animals are said to be quite white). Arranged in transverse rows upon the body are large tubercles, each of which under strong magnification will be found to end in a tiny hair. It is distinguished from _Trichoniscus pusillus_ by the larger size of its body, which is also comparatively broader, and from _Trichoniscus vividus_ by the four joints of the flagellum of its antennæ which latter have strong bristles upon them. In the former species there are five or more joints to the flagellum and the antennæ, though hairy, lack the bristles. _Trichoniscus roseus_ is to be looked for in old gardens.
_BRITISH LOCALITIES:--_
_England_: Warley; (W.M.W.): Maldon; (W.M.W. from R.M.): Stanmore; Hanwell; Ealing; Wimbledon; (W.M.W.): Berkhamsted; Torquay; (Norman, 49): Plymouth; (Bate and Westwood, 1 and B.M.,): Grassendale, near Liverpool; (R.W.): Newtownards; (R.W., Irish Nat, 1904, p. 260.)
_Scotland_: Tarbert; (Scot, 68).
_Ireland_: Dublin; Ballyfinder, Co. Down; (Scharff, 63): Templeogue; Dundrum; Blackrock; Rathgar, Co. Dublin; Bray, Co. Wicklow; (R.F.S.): Oakleigh; Kerry; (R.W.): Belfast; (Welch, Irish Nat., 1896, p. 213.): At the grave of Josiah Welch (grandson of John Knox), Castle Upton; Richhill, Co. Armagh; Castleconnell Ferry; (R.W.): Glenade House, Co. Antrim; (R.W. from R. Ll. Praeger).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Spain; (12): Italy; (59): Denmark; Germany; Holland; (39): Dalmatia; (18).
_Africa_: Algeria; Tunis; (24).
_Genus_--=TRICHONISCOIDES=, Sars, 1898 (59), p. 164.
_Abdomen narrow; eyes simple; (or wanting); flagellum, with four joints._
The members of this genus are very much like those of _Trichoniscus_. In the latter, however, the hinder legs are longer in proportion and the eyes are compound.
=Trichoniscoides albidus= Budde-Lund. PLATE VI.
1879 _Trichoniscus albidus_ Budde-Lund (7) p. 9. 1898 _Trichoniscoides albidus_ Sars (59), p. 165, pl. LXXIII., fig. 2.
We are able to include this species, as a specimen was found by Mr. Webb at Eton Wick in the summer of 1899. It is one of a number of species which the Rev. Canon Norman (49, p. 18) suggested as likely to be British. It is the only representative of its genus, which does not differ in any very important characters from the others in the family. The narrow elongated body will serve to separate it from _Trichoniscus vividus_ and _Trichoniscus roseus_, but on account of its size, which is much the same as that of _Trichoniscus pusillus_ and the two British species of _Haplophthalmus_, it will be advisable to give some further points of distinction. From the first its white colour will serve to differentiate it; the other two lack the narrow abdomen seen in _Trichoniscoides albidus_. Moreover, not one of the three shows the serrations on the side plates which characterise the species under consideration. _Platyarthrus hoffmannseggii_ is small and white and the edges of its side plates are toothed, but it is oval in shape, possesses no eyes, and its stout antennæ have but a single joint to the flagellum instead of four. On the Continent this species has been found in rich soil.
_BRITISH LOCALITIES:--_
_England_: Eton; (Stebbing, 71a): Sunderland; (Brady, 50a).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; Wimereux and Lyons, Forêt (25): Norway; Denmark; (59).
_Genus_--=HAPLOPHTHALMUS= Schöbl, 1850 (66), p. 449.
_Abdomen broad (comparatively); eyes simple; flagellum with three joints; back with longitudinal ridges._
The body of _Haplophthalmus_ is long in proportion to its width, but there is no abrupt decrease in the breadth of the abdomen as seen in _Trichoniscus_ and _Trichoniscoides_. The eyes are simple as in the latter genus and the lateral lobes of the head are rather large, while the side plates of the body are well separated.
=Haplophthalmus mengii= Zaddach. PLATE VII.
1844 _Itea mengii_ Zaddach (77), p. 16. 1860 _Haplophthalmus elegans_ Schöbl (66), p. 449. 1885 _Haplophthalmus mengii_ Budde-Lund (8), p. 250. 1898 _Haplophthalmus mengii_ Sars (59), p. 167, pl. LXXIV., fig. 1.
The Rev. Canon Norman discovered two specimens of this species in Ireland in June, 1900 (50); in the previous year one of us (Mr. Webb) found a single example at Eton Wick.
The main differences between the members of this genus and their allies are set forth in the generic description and incidentally elsewhere, so we shall content ourselves with giving the distinctive points of the two British species. _Haplophthalmus mengii_ has a number of raised longitudinal ribs on each segment of the thorax, the outer ridges being somewhat broken. There are also two prominent ribs upon the third segment of the abdomen.
_BRITISH LOCALITIES:--_
_England_: Eton; (Stebbing, 71a): Sunderland; (Brady, 50a).
_Ireland_: Corcumroe Abbey; Co. Clare (Norman, 50).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Norway; Prussia; Germany; Bohemia; (59).
=Haplophthalmus danicus= Budde-Lund. PLATE VIII.
1870 _Haplophthalmus elegans_ Budde-Lund (6), p. 228 (not _Haplophthalmus elegans_ Schöbl). 1879 _Haplophthalmus danicus_ Budde-Lund (7), p. 9. 1881 _Haplophthalmus mengii_ Weber (76), p. 192, pl. V., figs. 7-9 (not _Itea mengii_ Zaddach). 1885 _Haplophthalmus danicus_ Budde-Lund (8), p. 250. 1898 _Haplophthalmus danicus_ Sars (59), p. 168, pl. LXXIV., fig. 2.
This species was added to the British list by the Rev. Canon Norman (49), who found a colony in his garden at Berkhamsted. It has rows of tubercles on its thorax instead of ridges, and there are no ribs at all upon the abdomen. The front of the head projects further comparatively and forms a more acute point than in _Haplophthalmus mengii_ and it is not so purely white in colour as the latter species.
_BRITISH LOCALITIES:--_
_England_: Warley Place; (W.M.W. from Miss Willmott): Queen's Cottage, Kew Gardens; Stanmore; Hanwell, garden at Odstock, Bennett's Nurseries; (W.M.W.): Berkhamsted; (Norman, 49): Sunderland; (Brady, 50a).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Denmark; Holland; Germany; (Dollfus, Feu de Jeun, Nat., April, 1896): Norway; (Sars, 59).
_Section_--=ONISCI.=
THE OUTER DIVISIONS OF THE TAIL APPENDAGES BROADER THAN THE INNER ONES.
_Family_-ONISCIDÆ.
=Tail appendages projecting when the animal is walking.=
(1.) Unable to roll up into a complete ball.
_Genus_-=ONISCUS= Linné 1746 (41), p. 360.
_Flagellum, with three joints; abdomen broad; head with lateral lobes._
The characters given above taken in conjunction with the size of the animals will serve to distinguish the members of this genus.
=Oniscus asellus= Linné (The "Common Slater.") PLATE IX.
1761 _Oniscus asellus_ Linné (41), p. 500, No. 2058. 1792 _Oniscus murarius_ Cuvier (9), p. 22, pl. XXVI. 1838 _Oniscus fossor_ Koch (34), part 22, pl. XXII. 1868 _Oniscus asellus_ Bate and Westwood (1), p. 468. 1868 _Oniscus fossor_ Bate and Westwood (1), pp. 471-2. 1898 _Oniscus asellus_ Sars (59), p. 171, pl. LXXV.
_Oniscus asellus_ is one of the largest of our woodlice and it is also probably the commonest, though _Porcellio scaber_ is in many places quite as abundant. The body of _Oniscus_ is broad and expanded and the colour is usually a slate grey with yellowish markings more or less regularly arranged.
From the genus _Porcellio_ the species with which we are concerned is at once distinguished by the three jointed flagellum. _Porcellio_ has but two joints and has, besides, a prominent lobe projecting from the middle of the head, which is not seen in _Oniscus_. _Philoscia_, although it has three joints to the flagellum, has a narrow abdomen and lacks entirely the lateral lobes which are a feature of the other genera of Oniscidæ.
_Oniscus fossor_ of Koch (34) was recognized by Kinahan and by Bate and Westwood as a species. Dr. Scharff submitted specimens to Professor Budde-Lund who found no differences between them and _Oniscus asellus_. The former (63) mentions, however, that the characteristics of the supposed species are those of young examples of _Oniscus asellus_, and Professor Sars (59, p. 173) seems to be of the same opinion. Many young examples of _Oniscus asellus_ that we have examined have a curious whitish transverse band owing to the light colour of the dorsal plates of the first abdominal segments. The flagellum also does not seem to shew in young animals a distinct division into three joints.
_BRITISH LOCALITIES:--_
_England_: High Beach, Epping, including an albino; Maldon; Brightlingsea; Iver; Hanwell; Eton; Kew; Pamber Forest; Kingston-on-Soar; Bluebell Hill, Maidstone; (W.M.W.): Lynmouth; (W.M.W. from J.T.C.).
_Scotland_: (Scharff, 63). Dinnet, Aberdeenshire; (W.M.W. from Madame Christen).
_Ireland_: (Scharff, 63). Yellow form with black spots, Donegal (R.W.)
_FOREIGN DISTRIBUTION:--_
_Europe_: Almost throughout; (12): France; (25): Spain; (12): Sweden Norway; Denmark; Germany; Holland; Italy; Iceland; (59): Faroe Islands; Thorsharn; (R.F.S.)
_Africa_: Azores; (24).
_America_: Greenland; (59): North America; (Budde-Lund).
_Genus_--=PHILOSCIA= Latreille, 1804 (37), p. 43.
_Flagellum with three joints; abdomen narrow; head without lateral lobes._
If any further differences of an obvious kind be required to distinguish _Philoscia_ from _Oniscus_, one at least will be found in the much greater development of the hinder legs in the former genus.
=Philoscia muscorum= Scopoli. PLATE X.
[Not of Lereboullet, which is an _Oniscus_, see Bate and Westwood (1).]
1763 _Oniscus muscorum_ Scopoli (67), p. 415. 1793 _Oniscus sylvestris_ Fabricius (26), p. 397. 1793 _Oniscus agilis_ Koch in Panzer (51), part 9, pl. XXIV. 1833 _Philoscia marmorata_ Brandt (3), p. 183. 1838 _Ligia melanocephala_ Koch (34), part 22, pl. XVIII. 1847 _Zia melanocephala_ Koch (38), part 40, pl. I. p. 212. 1868 _Philoscia muscorum_ Bate and Westwood (1), p. 450. 1898 _Philoscia muscorum_ Sars (59), p. 174, pl. LXXVI., fig. 1.
This species lives chiefly at the roots of grass and under the stones or sticks that lie among it. _Philoscia muscorum_ has a very smooth and shining body, and its long legs enable it to move very rapidly. The ground colour of its dorsal surface varies from light yellow to deep brown. There are characteristic dark markings down the middle of the thorax and on the sides, between which are lighter patches. In dark coloured specimens the markings are by no means so evident.
_BRITISH LOCALITIES:--_
_England_: High Beach, Epping; Warley; (W.M.W.): Maldon; (W.M.W. from R.M.): Kew; Langley; Hanwell, yellow variation; Bluebell Hill, Maidstone; (W.M.W.): Liphook; (C.S.): Pamber Forest; Kingston-on-Soar; (W.M.W.)
_Scotland_: (Scott, 68).
_Ireland_: Almost throughout; (Scharff, 63).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Spain; (12): Sicily; (19): Hertsogovinia; (22): Sweden; (21): Norway; Denmark; Prussia; Germany; Holland; Poland; Austria; Italy; (59): Sardinia; (21).
_Africa_: Algeria; Tunis; (24).
=Philoscia couchii= Kinahan. PLATE XI.
1858 _Philoscia couchii_ Kinahan (33), p. 195, pl. XXIII., fig. 4. 1868 _Philoscia couchii_ Bate and Westwood (1), p. 1885 _Ligidium couchii_ Budde-Lund (8), p. 257. 1885 _Philoscia longicornis_ Budde-Lund (8), p. 221. 1897 _Philoscia couchii_ Dollfus (21), p. 72, pl. I., fig. 1.
_Philoscia couchii_ is an inhabitant of the sea-side; it is smaller than the last species, its colour to the naked eye is a uniform lead-grey, and its antennæ are very large (compared with its size) and hairy.
This species was discovered by Professor Kinahan when in the company of Messrs. Bate and Westwood near Polperro in Cornwall in the year 1858, and dried specimens presented by him are in the British Museum (Natural History).
_BRITISH LOCALITIES:--_
_England_: Talland Cove; Polperro; (Bate and Westwood, 1): Salcombe, Devon; (Norman, 49): Meadefoot, Torquay; (Stebbing in 49).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Spain; (12): Sicily; (19): Sebastopol; (Norman, 49).
_Africa_: Azores; Canaries; Morocco; Algiers; Tunis: Egypt Senegal; (24).
_Atlantic Isles_: Canaries; Azores; (21).
_Asia_: Syracuse; Bazone (18).
_Genus_--=PLATYARTHRUS= Brandt, 1833 (3), p. 174.
[_Typhloniscus_ Schöbl (66), p. 279.]
_Flagellum with one joint; eyes wanting; abdomen broad; habitat, ants' nests._
The broad body, which is much flattened, and the very thick antennæ distinguish _Platyarthrus_ from the other small woodlice (Trichoniscidæ).
=Platyarthrus hoffmannseggii= Brandt. PLATE XII.
1833 _Platyarthrus hoffmannseggii_ Brandt (3), p. 174, pl. IV., fig. 10. 1844 _Itea crassicornis_ Koch (34), part 36, pl. V. 1860 _Typhloniscus steinii_ Schöbl (66), p. 282. 1868 _Platyarthrus hoffmannseggii_ Bate and Westwood (1), p. 464. 1898 _Platyarthrus hoffmannseggii_ Sars (59), p. 175, pl. LXXVI., fig. 2.
Up to the present this is the only woodlouse which has been found in the nests of British ants. It is small and oval, its colour is white, and its body is covered with tubercles. The edges of its side plates are toothed, its flagellum has but a single joint and it has no eyes.
Miss Kate Hall tells us that, if very hungry, ants in captivity will kill and eat _Platyarthrus_. With regard to its own food, Lord Avebury has favoured us with the opinion that it lives on the spores of the lower plants, such as would be found in the ants' nest.
_BRITISH LOCALITIES:--_
_England_: Warley; Hanwell; West Drayton; Langley; Kingston-on-Soar; Bluebell Hill, Maidstone; (W.M.W.): Berkhamsted; Salcombe; Devon; Cheddar Cliffs, Somerset; (Norman, 49): Ide, near Exeter; (Parfitt, 53): Torquay; (Stebbing in 49); Lulworth Cove; (Rev. A. R. Hogan _teste_ Bate and Westwood, 1): Hammersmith; Oxford; Berry Head, Torquay; Plymouth; (Bate and Westwood, 1): In the nest of _Myrmica rubra_, Newton Ferrers (E. E. Lowe).
_Scotland_: Banff; (Thomas Edward in 49).
_Ireland_: Leixlip, Co. Dublin; Lismore, Co. Waterford; Glengariff, Co. Cork; (Scharff, 63): Bagenalstown, Co. Carlow; (64).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (28): Spain; (12): Denmark; Germany; Holland; Bohemia; Austria; Tyrol; Helvetia; (59).
* * * * *
NOTE.--In the genera which follow, air-tubes or air-cavities (tracheæ) are present in the outer plates of the abdominal appendages, 1 and 2, or 1 to 5. The appendages in question have in consequence a milk-white appearance in the living animal owing to the fact that the enclosed air reflects white light. Considerable interest attaches to the study of these tracheæ, which have the same function as those of insects, but which have been independently developed. To emphasise the latter fact the structures are often termed "pseudotracheæ."
_Genus_--=PORCELLIO= Latreille, 1804 (37), p. 45.
_Flagellum, with two joints; abdomen, broad; frontal lobe projecting._
_Porcellio_ is easily separated from the previous genera--_Oniscus_, _Philoscia_, and _Platyarthrus_--by its two-jointed flagellum. The fact that the abdomen is not abruptly narrowed separates it from _Metoponorthus_, which also lacks the prominent frontal lobe so characteristic of _Porcellio_. The species of this genera might be confused with _Cyclisticus_ which has two joints to the flagellum and a broad abdomen, but the latter genus has the power of rolling itself into a ball, while its frontal lobe is very small, and the first segment of its thorax is comparatively larger than in any species of _Porcellio_.
=Porcellio scaber= Latreille. PLATE XIII.
1804 _Porcellio scaber_ Latreille (37), p. 45. 1818 _Oniscus granulatus_ Lamark (36), p. 261. 1818 _Porcellio nigra_ Say (62), p. 432. 1840 _Porcellio brandtii_ Milne-Edwards (46), p. 168. 1840 _Porcellio dubius_ Koch (34), part 34, pl. VIII. 1847 _Porcellio asper_ Koch (35), p. 207, pl. VIII., fig. 98. 1857 _Porcellio montezumæ_ Saussure (60), p. 207. 1865 _Porcellio paulensis_ Heller (31), p. 136, p. XII., fig. 5. 1868 _Porcellio scaber_ Bate and Westwood (1), p. 475. 1876 _Porcellio graniger_ Miers (44), p. 223. 1885 _Porcellio graniger_ Budde-Lund (8), p. 149. 1898 _Porcellio scaber_ Sars (59), p. 176, pl. LXXVII.
The body of _Porcellio scaber_ is densely covered with tubercles. Its colour is usually of a very dark grey, but at times it is quite red or variegated with yellow. Albino specimens have been recorded. The two joints of the flagellum are of the same length and together equal that of the last joint of the peduncle. Air-tubes are present in the outer plates of the first two abdominal appendages.
_BRITISH LOCALITIES:--_
_England_: High Beach, Epping; Warley; Brightlingsea; (W.M.W.): Maldon; (W.M.W. from R.M.): Langley; Kew; Skirmett; Pamber Forest; (W.M.W.): Liphook; (C.S.): Stoke-on-Trent; Kingston-on-Soar; (W.M.W.)
_Scotland_: Dinnet (W.M.W. from Madame Christen).
_Ireland_: Common everywhere; (Scharff, 63.)
_FOREIGN DISTRIBUTION:--_
_Europe_: Throughout; (59): France; (28): Spain; (15): Iceland; (59): Faroe Isles--Thorsharn and Naalsoe--(R.F.S. and B.M., N. Annadale).
_America_: Greenland; North America; Sandwich Isles; (B.M.); Mexico; (59): St. Paul; St. Croix; (59); Ascension; Tristan d'Acunha; (23)
_Asia_: Ceylon; Kamtschatka: (23).
_Australia_: Melbourne; Sydney; Tasmania; New Zealand; (B.M., Chilton).
_Africa_: Azores; Canaries; Cape of Good Hope; (24).
=Porcellio pictus= Brandt and Ratzeburg. PLATE XIV.
1833 _Porcellio pictus_ Brandt and Razteburg (4), p. 78, pl. 12, fig. 5. 1839 _Porcellio melanocephalus_ Koch (34), part 28, pl. XVIII. 1853 _Porcellio melanocephalus_ Schnitzler (65), p. 24. 1856 _Porcellio mixtus_ Fitch (29), p. 120. 1868 _Porcellio pictus_ Bate and Westwood (1), p. 1898 _Porcellio pictus_ Sars (59), p. 177. pl. LXXVII., fig. 1.
There are tubercles on the body of _Porcellio pictus_, which is a striking looking animal. Its head is black with the lateral lobes curved outwards; there is a dark band down the middle of the back and commonly two others on each side, with more or less conspicuous yellow markings between.
The distal (terminal) joint of the flagellum is but half the length of the proximal one and the last peduncular joint is longer than the two combined.
The abdominal appendages--1 and 2--are provided with air-tubes.
_BRITISH LOCALITIES:--_
_England_: Maldon; (W.M.W. from R.M.): Chislehurst; (Bate and Westwood, 1): Cooper's Hill, near Cheltenham; (Norman, 49): Exeter; (Parfitt, 53): Kent; (Bate and Westwood, 1.)
_Scotland_: Between Leith and Portobello; (Scott, 68): Cumbrae (Scott, 68a): Ayrshire; (Boyd in Norman, 49): Banff; (T. Edwards in Norman, 49).
_Ireland_: Dublin; Belfast; (Bate and Westwood, 1): Galway; Maryborough; Queen's Co., Castel; and Caher Co. Tipperary; (R.F.S.)
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): North, West-Central, and East Europe; (8): Sweden; Norway; Denmark; Germany; Hungary; Russia; (59).
_North America_: (8).
=Porcellio dilatatus= Brandt. PLATE XV.
1833 _Porcellio dilatatus_ Brandt and Ratzeburg (4), p. 78, pl. 12., fig. 6. 1840 _Porcellio scaber_ Milne-Edwards (not Latreille) (46), p. 167. 1868 _Porcellio dilatatus_ Bate and Westwood (1), p. 1898 _Porcellio dilatatus_ Sars (59), p. 179, pl. LXXVII., fig. 2.
The fact that _Porcellio dilatatus_ is more than half as broad as it is long, at once distinguishes it from the other species of _Porcellio_. It is tuberculated and of somewhat a lighter grey than _Porcellio scaber_ usually is. The two species agree in having the two joints of the flagellum equal, but the last peduncular joint, as in _Porcellio pictus_, is longer than the flagellum.
As in the two preceding species, air-tubes are found in the outer plates of the appendages on the first two abdominal segments. _Porcellio dilatatus_ is to be looked for near houses.
_BRITISH LOCALITIES:--_
_England_: Maldon; (W.M.W. from R.M.): Eton; (Stebbing from W.M.W., 71a): Berkhamsted; (Norman, 50): Headley, Surrey; Ventnor; (Stebbing in Norman, 49).
_Ireland_: Dublin; (Scharff, 63): Dundrum; (Scharff in Norman, 50): Galway; Roundstone; (R.F.S.): Belfast; (C. W. Buckle, Irish Nat., Vol. XI. (1902), p. 43).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Spain; (12 ): Denmark; Norway; Germany; Poland; Holland; (59).
_Africa_: Madeira; Azores; (24).
_Australia_: New Guinea; (59).
=Porcellio rathkei= Brandt. PLATE XVI.
1833 _Porcellio rathkei_ Brandt (3), p. 177, fig. 10. 1833 _Porcellio ferrugineus_ Brandt (3), p. 178. 1840 _Porcellio trilineatus_ Koch (34), part 34, pl. IX. 1853 _Porcellio trivittatus_ Lereboullet (39), p. 54, pl. I., figs. 13 and 14. 1853 _Porcellio tetramoerus_ Schnitzler (65), p. 24. 1853 _Porcellio striatus_ Schnitzler (65), p. 24.
There is often a light band down the back and one on either side of it near the margin in _Porcellio rathkei_ (especially in the males), with other more irregularly arranged light patches between. Unlike the three species previously considered, the present one has a smooth body. The distal joint of the flagellum is the longer, and the flagellum itself is equal in length to the last joint of the peduncle.
Some specimens found by Mr. Webb in 1899 at Eton were submitted to Mr. Stebbing, and since then the former has found _Porcellio rathkei_ to be pretty generally distributed in West Middlesex, where the species appears to frequent the open fields.
Air-tubes occur in abdominal appendages 1 to 5 and the white appearance of all of these at once serves to distinguish the living animal from _Porcellio scaber_ in which the first two pairs of abdominal appendages alone are white.
_BRITISH LOCALITIES:--_
_England_: Eton; (Stebbing, 71a): Lane End; (Stebbing, from the Misses Johnston, 71a): Acton; Ealing; Hanwell; Southall; Northolt; Greenford; West Drayton; Mortlake; (W.M.W.); Sunderland; (Brady, 50a).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Bosnia; Servia; (22): Hertzogovania (B.M.); Norway; Northern, Western, and Middle Europe, everywhere; (59): Corfu (B.M.)
_Asia_: Transcaucasia; (59).
_North America_: (59).
=Porcellio laevis= Latreille. PLATE XVII.
1804 _Porcellio laevis_ Latreille (37), p. 46. 1827 _Porcellio degeerii_ Savigny and Audouin (61), p. 289. 1833 _Porcellio cucercus_ Brandt (3), p. 177. 1833 _Porcellio syriacus_ Brandt (3), p. 178. 1833 _Porcellio musculus_ Brandt (3), p. 180. 1833 _Porcellio cinerascens_ Brandt (3), p. 178. 1833 _Porcellio dubius_ Brandt (3), p. 178. 1837 _Porcellio poeyi_ Guérin (30), p. 6. 1844 _Porcellio urbicus_ Koch (34), part 36, pl. IV. 1847 _Porcellio flavipes_ Koch (35), p. 206, pl. VIII., fig. 97. 1853 _Cylisticus laevis_ Schnitzler (65), p. 25. 1857 _Porcellio cubensis_ Saussure (60), p. 307. 1857 _Porcellio sumichtasli_ Saussure (60), p. 307. 1857 _Porcellio cotillæ_ Saussure (60), p. 307. 1857 _Porcellio aztecus_ Saussure (60), p. 307. 1857 _Porcellio mexicanus_ Saussure (60), p. 307.
Another smooth species is _Porcellio laevis_. The colour of its body is light grey with irregular white markings. The large size of this species and the very long tail-appendages of the males are features which will help to identify it. The distal joint of the flagellum is slightly the longer and as in the last species (_P. rathkei_) the flagellum is equal in length to the last joint of the peduncle. The chief habitats for this species are among vegetable rubbish near human dwellings.
Only the first two abdominal appendages contain air-tubes.
_BRITISH LOCALITIES:--_
_England_: Maldon; (W.M.W. from R.M.): Ipswich (1892); Hanwell; Wimbledon; (W.M.W.): Kent; (Kinahan, 32).
_Ireland_: Dublin; (Bate and Westwood, 1): Blackrock Dundrum; Co. Dublin; Galway; (R.F.S.)
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Spain; (15): Sicily; (19): Hertzogovania; (22): Sweden; Denmark; Germany; Belgium; Austria; Italy; Dalmatia; Greece; Turkey; (59); Corfu; (B.M.): Inca, Majorca (23); (B.M.--Pocock and Thomas.)
_Asia_: Syria; Turkestan; (21).
_Africa_: Morocco; Algeria; Tunis; Tripoli; Senegal; Egypt; (23).
_Atlantic Isles_: Bermudas; Azores; Canaries; Cape Vera; Madeira; (24).
_America_: North America; Mexico; Peru; Brazil; Chili; West Indies; Pacific Islands; (59); Sandwich Isles; (B.M.)
=Porcellio ratzeburgii= Brandt. PLATE XVIII.
1833 _Porcellio ratzeburgii_ Brandt, (3), p. 178. 1839 _Porcellio nemorensis_ Koch (34), part 28, pl. XIX. 1839 _Porcellio lugubris_ Koch (34), part 28, pl. XX. 1853 _Porcellio quercum_ Schnitzler (65), p. 24. 1898 _Porcellio ratzeburgii_ Sars (59), p. 182, pl. LXXX, fig. 1.
There are granulations on the middle of the segments in _Porcellio ratzeburgii_ and the sides of its body are more nearly parallel than in the other species of _Porcellio_; the frontal lobe is, practically speaking, semicircular and the lateral plates of the thorax flank the head to a considerable extent. As in _Porcellio pictus_, the dark band is in the middle of the back. The distal joint of the flagellum is nearly twice as long as the proximal, and the flagellum is shorter than the last joint of the peduncle. This species was added to the British list by Mr. Webb (74) in 1898.
_Porcellio ratzeburgii_ agrees with _Porcellio rathkei_ in having air-tubes in the first five abdominal appendages.
_BRITISH LOCALITIES:--_
_England_: Warley; Brightlingsea; young examples (W.M.W.): Maldon; young examples (W.M.W. from R.M.)
_FOREIGN DISTRIBUTION:--_
_Europe_: Trafoi St. Martini, and Capitello, in the Tyrol; (Norman, 50); East Alps, very common; Val-de-Joux; Massif de la Chartreuse Vaulnaveys (25): Bosnia; (22): Norway; Central Europe; Upper Pfaltz; Bohemia; Saxony; Rhaetia; (59).
_Genus_--=METOPONORTHUS= Budde-Lund, 1879 (7), p. 4. _Porcellionides_ Miers, 1876 (44), p. 98.
_Flagellum, with two joints; abdomen, narrow; frontal lobe not developed._
The hinder legs of _Metoponorthus_ are proportionately longer than in any other Oniscidæ save _Philoscia_. Both genera have a narrow abdomen, but _Philoscia_ has an extra joint to the flagellum, and shows no sign of lateral lobes to the head.
=Metoponorthus pruinosus= Brandt. PLATE XIX.
1833 _Porcellio pruinosus_ Brandt (3), p. 181. 1840 _Porcellio truncatus_ Milne-Edwards (46), p. 173. 1840 _Porcellio maculicornis_ Koch (34), part 34, pl. XVI. 1853 _Porcellio frontalis_ Lereboullet (39), p. 63, pl. I, fig. 17. 1868 _Porcellio pruinosus_ Bate and Westwood (1), p. 487. 1877 _Porcellio (Porcellioides) flavo-vittatus_ Miers (45), p. 669, pl., LXVIII., fig. 4. 1898 _Metoponorthus pruinosus_ Sars (59), p. 184, pl. LXXX., fig. 2.
Undamaged specimens of _Metoponorthus pruinosus_ are of a beautiful bluish-grey colour, owing to a "bloom" which is easily brushed off, revealing a dark reddish-brown tint beneath it. The antennæ are long and have white markings upon them.
Air-tubes occur in the first two abdominal appendages.
_BRITISH LOCALITIES:--_
_England_: Maldon; (W.M.W. from R.M.): Hanwell; Eton Wick; Kew; Ipswich; Stoke-on-Trent; (W.M.W.): Chiselhurst; Oxford; (Bate and Westwood): Berkhamsted; Burnmoor; Durham; (Norman, 49): Exeter; (Parfitt, 53); Torquay; (B.M.--T.R.R.S.)
_Scotland_: Banff; (Thomas Edwards in Norman, 49)
_Ireland_: Dublin; (Kinahan, 32): Foyle District; Donegal; Galway; Clonbrock, Co. Galway; Mornington, Co. Meath; Santry; Gleeson Park; Dundrum, Co. Dublin; Bray; (R.F.S.)
_FOREIGN DISTRIBUTION:--_
_Europe_: Practically all the Countries of Europe are given in Dollfus' list; (23).
_Asia_: Japan; China; Syria; Ceylon; Sumatra; Celebes; Phillipines; Caucasus; Himalayas; (23): Christmas Island; (B.M.)
_Africa_: Generally distributed; Madagascar; Seychelles; (23).
_Atlantic Isles_; (23).
_America_: North and South, almost everywhere, to judge from M. Dollfus' list; (23).
_Australia_: New Caledonia; (23).
=Metoponorthus cingendus= Kinahan. PLATE XX.
1857 _Porcellio cingendus_ Kinahan (32), p. 279, pl. XIX., figs. 1468-9. 1868 _Porcellio cingendus_ Bate and Westwood (1), p. 489. 1885 _Metoponorthus simplex_ Budde-Lund (8), p. 188.
The colour of _Metoponorthus cingendus_ is steel blue with red or yellowish spots. It has a raised line across each thoracic segment and its abdomen is narrower than in _Metoponorthus pruinosus_.
_BRITISH LOCALITIES:--_
_England_: Salcombe, Devon; (Norman, 49): South Devon; (Stebbing in 49).
_Ireland_: Dublin; (B.M. from Kinahan); Mountain Districts of Dublin, Wicklow, and Cork; Coast of Kerry; Arran Islands; Achill, Co. Mayo; Roundstone, Co. Galway; Mallow, Caef Island; Glandore; Brock Haven, Co. Cork; Killoughrim Forest, Co. Wexford; Kenmare, Co. Kerry; (R.F.S.).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Spain; (12).
(2.) Able to roll up into a ball.
_Genus_--=CYLISTICUS= Schnitzler, 1853 (65), p. 24.
_Flagellum, with two joints; abdomen broad; frontal lobe, very small._
The characters given immediately above are almost those of _Porcellio_ with which _Cylisticus_ might, perhaps, be confounded. The latter has the power, however, of rolling itself into a ball, and the first segment of the thorax is comparatively larger than in any species of _Porcellio_, indeed the side plates of the segment in question entirely flank the head. These features, as well as the straight sides of the body and the arched back, connect _Cylisticus_ with _Armadillidium_, from which the former is, however, at once separated by its long pointed tail appendages.
=Cylisticus convexus= De Geer. PLATE XXI.
1778 _Oniscus convexus_ De Geer (10), p. 553, pl. XXXV., fig. 11. 1833 _Porcellio spinifrons_ Brandt (3), p. 177. 1836 _Porcellio laevis_ Koch (34), part 6, pl. I. 1853 _Porcellio armadilloides_ Lereboullet (39), p. 65. pl. I., fig. 18. 1853 _Cylisticus laevis_ Schnitzler (65), p. 25. 1868 _Porcellio armadilloides_ Bate and Westwood (1), p. 485. 1898 _Cylisticus convexus_ Sars (59), p. 186, pl. LXXXI.
There is but a single species of _Cylisticus_ found in this country, so that it is not necessary for us to go into much further detail with regard to it. _Cylisticus convexus_ has the two joints of the flagellum about equal, and they together in turn closely approximate in length to the last joint of the peduncle. Mr. Stebbing says, in a letter, that British examples do not appear to have the "white tail-piece" seen in Continental ones. It is not noticeable in the preserved specimens which we have seen from Berkhamsted and Leixlip, but it is very evident in the living ones found at Hanwell and Maidstone.
The abdominal appendages 1 to 5 are provided with air-tubes.
_BRITISH LOCALITIES:--_
_England_: Maldon; (W.M.W. from R.M.): Hanwell; Bluebell Hill, Maidstone; Eton; (W.M.W.): Berkhamsted; Portland; (Norman, 49).
_Scotland_: Salisbury Crags; Edinburgh; Lanarkshire; Rothesay; (Scott, 68): Killwinning; (John Smith _fide_ Robertson, 57): Highgate; (Bate and Westwood, 1).
_Ireland_: Leixlip, Co. Dublin; Tempo, Co. Fermanagh; Goresbridge, Co. Kilkenny; (R.F.S.)
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (25): Sweden; Norway; Denmark; Germany; Bohemia; Holland; Belgium; Turkey; Caucasus; (59).
_North America_; (59).
_Family_--ARMADILLIDIIDÆ.
=Tail appendages not projecting when the animal is walking.=
_Genus_--=ARMADILLIDIUM= Brandt, 1833 (3), p. 184.
_Flagellum, with two joints; outer division of the tail appendages expanded and broader at the hinder end._
The members of the genus _Armadillidium_ are more likely to be confounded, by the uninitiated, with the "Pill-millipedes" than with other Woodlice. Excepting _Cylisticus_ (which has long pointed tail appendages) no other British forms have the power of rolling themselves up into a complete ball. The very arched body is characteristic of _Armadillidium_, and so is the groove into which the basal joints of the antennæ fit when the creatures curl up.
The first two abdominal appendages only are provided with air-tubes.
=Armadillidium nasatum= Budde-Lund. PLATE XXII.
1885 _Armadillidium nasatum_ Budde-Lund (8), p. 51. 1892 _Armadillidium nasatum_ Dollfus (14), p. 10, fig. 12. 1899 _Armadillidium nasatum_ Norman (misprinted _Porcellidium_) (49), p. 57. pl. VI., figs. 5-8.
_Armadillidium nasatum_ has a narrow but very prominent frontal lobe, which is almost square and curves somewhat upwards and backwards. The joints of the flagellum are approximately equal, and are together of the same length as the last peduncular joint.
The telson is as long as it is broad at the base, and tapers to a roundish point, while its sides are slightly incurved.
The outer divisions of the tail appendages are considerably longer than broad, and are more or less paddle-shaped.
It will be noticed that the slope from thorax to telson is more gentle than in the common species, _Armadillidium vulgare_, and the first thoracic segment is not so greatly developed. Consequently the species which we are considering does not produce a perfect sphere, and the antennæ are not hidden when it rolls up. It is interesting to compare this species with _Cylisticus convexus_. The surface of the body is smooth, and its colour is a delicate brownish grey with more or less distinct rows of darker markings.
_BRITISH LOCALITIES:--_
_England_: Maldon; (W.M.W. from R.M.): Bluebell Hill, Maidstone (W.M.W.); Clifton, banks of the Avon; (W.M.W. from J.T.C. 1900): Leigh Woods, Clifton; Tunbridge Wells; South Devon; (Stebbing in 49); Cheddar Cliffs, Somerset; (Norman, 49).
_FOREIGN DISTRIBUTION:--_
_Europe_: France; (28): Spain; (12): Italy; (23).
=Armadillidium vulgare= Latreille. PLATE XXIII.
1804 _Armadillo vulgaris_ Latreille (37), p. 48. 1804 _Armadillo variegatus_ Latreille (37). 1853 _Armadillo ater_ Schnitzler (65), p. 48. 1816 _Armadillo maculatus_ Risso (56), p. 158. 1818 _Armadillo pillularis_ Say (62), p. 432. 1825 _Armadillo pustulosus_ Dermarest (11), p. 323, pl. XLIX. 1830-4 _Armadillidium commutatum_ Brandt and Ratzeburg (4), p. 81, pl. XIII., fig. 123. 1833 _Armadillidium zenckeri_ Brandt (3), p. 185. 1839 _Armadillo trivialis_ Koch (34), part 28, pl. XIV. 1898 _Armadillidium vulgare_ Sars (59), p. 189, pl. LXXXII.
The common pill woodlouse is _Armadillidium vulgare_. Its frontal lobe is not large, though it is broad, while its margin where it joins the head is rounded and slightly recurved. The proximal joint of the flagellum is somewhat the shorter and the two together, as in _Armadillidium nasatum_, are of about the same length as the last joint of the peduncle.
The telson has the form of a triangle with the angles truncated and is about as long as it is broad at the base. The outer divisions of the tail appendages are considerably broader than they are long.
The species can roll itself up into a very perfect sphere, and when it assumes this form its antennæ are hidden beneath the much expanded lateral plates of the first thoracic segment.
The body is smooth, shiny, and strongly arched. Its colour varies very considerably, generally it is of a slaty-grey, but yellow markings are often present to a greater or less extent. In a specimen before us (from Bluebell Hill, Maidstone) the head is of a uniform dark grey, the sides of the thorax are yellow, while the back is mottled with the same colour. The abdomen, including the telson, is also yellow with the exception only of the tail appendages, which are dark grey.
_BRITISH LOCALITIES:--_
_England_: Warley; (W.M.W): Maldon; (W.M.W. from R.M.): Brightlingsea; Hanwell; Mortlake; Bluebell Hill, Maidstone; Langley; Skirmett; Pamber Forest; Kingston-on-Soar; Ipswich; (W.M.W.); Lynmouth; (W.M.W. from J.T.C.)
_Scotland_: (Scott, 68.)
_Ireland_: Ardrahan; (Norman, 50): Borris, Co. Carlow; Glandare, Terneay, Co. Cork; Courtstown, Co. Wexford; Cappagh, Co. Waterford; Castel, Co. Tipperary; (R.F.S.)
_FOREIGN DISTRIBUTION:--_
_Europe_: Throughout; (23).
_Asia_: Damascus; (23).
_Africa_: Algeria; (23).
_Atlantic Isles_: (23).
_America_: North and South; (23).
_Australia_: Melbourne (64 quoting Budde-Lund); New Zealand; (23).
=Armadillidium pulchellum= Zencker. PLATE XXIV.
1799 _Oniscus pulchellus_ Zencker (78) (quoted by Koch in Panzer),