CRUSTACEOLOGY. 



40,5 



Crustacea, dric, and very convex body, with seven joints inde- 

 *-— Y^— * pendent of the head, tail, and five narrow segments at 

 the base of the latter ; central caudal fin subovate, with 

 two smaller lateral ones on each side, which, when 

 spread, give it a quinquedentate appearance : antenna? 

 four, short, the upper pah- not half so long as the other; 

 legs fourteen ; feet of the foremost six broad, serrated 

 on the inside; all armed with a single claw. 



" Length an inch; breadth not quite a quarter. Co- 

 lour pale yellow, clouded with cinereous on the sides." 

 €6. Cymc- Genus LXVI. Cymotiioa. Tail composed of a great 

 i uoa. many segments, the last at its base bearing a double 



appendage on each side. Most of the segments bearing 

 feet, their lateral margins being thickened. Antennae 

 setaceous and many-jointed, inserted one pair above the 

 other, under the clypcus. Feet with strong, sharp nails. 

 Am!u«. Sp. 1. Asilus. Head with three protuberances or 



lobes on the hinder part : the hinder segments (the last 

 excepted) arched backwards; the last segment semi- 

 elliptical. 



Inhabits the European ocean. 



Oniscus asilus of Linne and Pallas; Cymalhoa asilus 

 of Fabricius and Latreille. 

 <E;trum. Sp. 2. (Estrinn. Body oblong oval, the last segment 



transverse. 



Inhabits the European Ocean. 



Oniscus oestrum of Linne and Pallas; Cymothoa oes- 

 trum of Fabricius and Latreille. 



Observation. It is highly probable that Oniscus tes- 

 tudo of Montagu (Transactions of the Linnean Society 

 of London, vol. ix. page 102. tab. 5. fig. 5.) is referable 

 to a genus akin to this ; but as we have never had an 

 opportunity of examining this species, we cannot speak 

 with certainty on this head, but content ourselves by 

 quoting the description given by that author. 



" Oniscus testudo. Body subovate, composed of eight 

 joints, rising to a ridge on the back; the plates elevated 

 on their edges; the four first fall very low on the sides, 

 and obscure the anterior legs ; along each side of the 

 body a row of small tubercles : the front sub-bifid : an- 

 tennae four, very short, the lower pair hid beneath: eyes 

 prominent and black; posterior end obtusely pointed ; 

 caudal fins beneath, obscure ; legs fourteen, short and 

 strong, the three posterior pairs longest ; all furnished 

 with a simple claw. 

 " Length two lines-. 



" Colour dull red, with a white spot on the anterior 

 part of the back, but as the animal dies this mark is lost. 

 Rare." 

 67. Sphje- Genus LXVII. SphjEroma. Tail composed of two 

 •em. segments ; the last furnished with a double lateral fo- 



liaceous appendage, placed on a common footstalk on 

 each side. Body oval, capable of rolling into a globu- 

 lar form, composed of seven joints. Antennae setaceous 

 and many jointed, inserted by pairs one above the other; 

 their bases placed very close together ; the upper pair 

 with a very large peduncle. 

 Scrota. Sp.\. Serrata. Body smooth ; the anal segment of the 



tail rounded, the sides obliquely truncated; the lamella 

 equal, elliptical, with their points sharp. 



Oniscus globti tor of Pallas; Cymoihoa serrata of Fa- 

 , bricius ; Sphairama cinerea of Latreille. 



Inhabits the European Ocean ; is very abundant on 

 several of our reeky coasts in pools left by the tide ; 

 when touched, it contracts into a ball. Length nearly 

 half an inch. Colour, when alive, cinereous, very beau- 

 tifully speckled with black. 

 Rugicaada. Sp. 2. liugkauda. Body smooth ; the anal segment 



rough, rounded at the apex'; the sides obliquely trunca- Crustacea. 

 ted; the lamellae equal, their points somewhat rounded, ""-v"" -* ' 



Sphceroma r/igicauda, Leach's MSS. 



Inhabits the Atlantic Ocean. 



It was discovered on the shore of Ulva, one of the 

 Western Isles of Scotland, by Mr Leach : he observed 

 that it was more agile than Sphceroma cinerca, from 

 which species it is readily distinguished by the rough- 

 ness of the anal segment, and the smaller size of the 

 peduncle of the superior antennae. He has since ob- 

 served it in very great plenty near the Ware-head, on the 

 river Tamer, in Devon, where the water is but brackish ; 

 a curious contrast with the original habitat in the At- 

 lantic ! 



Colour, when alive, cinereous, very beautifully speck- 

 led and streaked with black. Eyes black. Length 

 about one-third of an inch. 



Genus LXVIII. Nes^ea. Apex of the tail on each 68. Nm*». 

 side with a single foliaceous appendage placed on a 

 footstalk. Body oblong. Antenna; setaceous, and near- 

 ly of an equal length ; the upper pair with a very large 

 double-jointed peduncle, (the basilar joint largest,) 

 which occupies nearly half their length. Space between 

 the antennae very visible. Body composed of six jointi, 

 the last largest. 



Sp. 1. Biden'ata. Last segment of the body armed Bidentata. 

 with two spines or teeth. 



Oniscus bidentatu, Linnean Transactions. 



Ncesea bidentatas, Leach's MSS. 



Inhabits the British ocean: the living specimens 

 we have seen were cinereous, faintly streaked with 

 red. 



Genus LXIX. Campecopea. Base of the tail armed eg, c, , M . ' 

 with a bent foliaceous process on each side. Body com- ptcoriiA. 

 posed of six joints. Antennae setaceous, the upper 

 pair longest, with the peduncle composed of two visible 

 joints ; the intermediate space between the superior an- 

 tennae very great. 



Sp. 1. Hirsuta. Body hirsute. Hirswta, 



Oniscus hirsutus, Montagu, Lin. Trans, vol. vii. t. 6. 

 f. 8. Campecopea hirsuta, Leach's MSS. 



Colour (according to Montagu) brown, with some- 

 times a few faint bluish spots on the posterior joint. 

 Length one-eighth of an inch. 



Inhabits the European ocean, but is rather rare. 



II. The antennae obscure, or entirely wanting. 



Genus LXX. Bopyrus. Body depressed, of an in- 70. Borr. 

 curvate oval form. The under part on each side with Rt " 3 - 

 four foliaceous marginal appendices. Feet minute, 

 spurious, bent, and placed on the margin. The last 

 segment of the tail small. 



Sp. 1. Squillarum. Colour pale greenish. Sqr.iUa uib 



Monocuhis crangorum of Fabricius. Bopyrc des- 

 crustaccs of Bosc. Oniscus squillarum of Montagu. 

 Bopyius squillarum of Latreille. 



Inhabits the European ocean, dwelling under the 

 thoracic plate of the prawn ( Palccmon squilla) or shrimp 

 (Crangon vulgaris), and causing a tumour on the sides 

 of the animal. It varies much in shape, taking the 

 form of the shell. It is so common, that it is surpriz- 

 ing it should have escaped the notice of all British natu- 

 ralists until it was described in the ninth volume cf the 

 Linnean Transactions, by George Montagu, Esq. It 

 was first described in the Memoirs (if the Academy of 

 Sciences, in the year 1772, page 29, pi. I. 



01 servalion. Mr Montagu has described an animal 

 as inhabiting the thoracic plate of Callianassa sub- 

 terranea; and as we have never seen the species, we 



