CRUSTACEA. 181 



C. hir&ula, Leach. Brown, the last joint of the body with a few 

 faint bluish spots. ^ inch long. Inhabits coasts of Devonshire. 

 Lin. Trans, vii. pi. 6, fig. 8. 



Gen. 13. N.ESA, Leach. Oniscus, Adams. 

 Tail on each side of the last segment with a subcompressed pro- 

 cess attached to a peduncle ; body six-jointed, the last seg- 

 ment largest ; antennae setaceous, subequal, upper ones with 

 a very large biarticulated peduncle, the first joint largest ; 

 claws bifid. 



N. bidentata, Leach. Last segment of the body with two spines or 

 teeth ; colour cinereous, faintly streaked with blue or reddish. 

 Inhabits coasts of Wales and Devonshire. Lin. Trans, xi. 367- 



Gen. 14. DYNAMENE, Leach. 



Eyes not reaching to the anterior margin of the first segment of 

 the body ; body in seven segments ; tail with two equal fo- 

 liaceous appendages on each side of the base ; apex notched ; 

 claws bifid. 



D. Montagui, Leach. Body sublinear ; sixth joint with a flattened 

 prolongation ; two tubercles at the last segment of the abdomen. 

 Inhabits British shores Lin. Trans, xi. 308. 



Gen. 15. CYMODOCEA, Leach. Oniscus, Mont. 

 Eyes touching the interior margin of the first segment of the 

 body ; body in seven segments ; tail with two subcompressed 

 but not foliaceous appendages at the base, the exterior ones 

 longest ; apex of the tail notched, with a lamella in the cen- 

 tre ; claws bifid. 



C. truncata, Leach. Apex of the tail truncate; abdomen 



granulated ; third and four segments of the abdomen with each 

 two dorsal tubercles. Coasts of Devonshire. Lin. Trans, xi. 303. 



FAMILY IV. ASELLOTA. 



Last segment of the abdomen destitute of swimming appendages. 

 Gen. 16. ASELLUS, Geoff. Idotea, Fab. 



Intermediate antennae with four, the exterior with five joints ; 

 eyes small, simple and lateral ; exterior feet-jaws united at 

 the base in form of a lip, with their first joint large and la- 

 melliform ; body oblong, depressed, of seven segments ; tail 

 of one large and rounded joint with two forked appendages, 

 terminated by two conical and diverging filaments, or two 

 small tubercles ; branchiae vesicular, oval, to the number of 

 six ; seven pairs of feet, terminated by a simple hook. 



A. vulgaris, Lat. Colour cinereous, spotted with gray or whitish. 

 4 or 5 lines long. Inhabits ponds and ditches in Europe. B 

 Lin. Trans, xi. 373. 



