ORDER ISOPODA. 
215 
hooks. They have at their base ail elongated vesicular body. 
These laemodipods form the subgenus of Cyamus (proper), 
Lat. Larunda, Leach, ( Oniscus ceti, Lin.) 
THE FIFTH ORDER OF CRUSTACEA. 
ISOPODA, 
Polygonata, Fab., the genus Monoculus excepted, 
Approach the hemodipods by the want of palpi to the mandi- 
bles, but they are remote from them in many respects. The 
two anterior feet are not annexed to the head, but depend, as 
well as the following, on a peculiar segment ; they are always 
fourteen in number, unguiculated, and without vesicular ap- 
pendage at the base. The under part of the tail is furnished 
with very apparent appendages, in the form of leaflets or vesi- 
cular pouches, and the first or the exterior two usually cover 
totally, or in a great part, the others. The body is generally 
flatted, or more wide than thick. The mouth is composed of 
the same pieces as in the preceding Crustacea ; but here the 
parts which correspond to the two upper jaw-feet of the deca- 
pods present still more than in these last the appearance of a 
lower lip, terminated by two palpi. Two of the autenme, the 
middle, are almost obliterated in the last Crustacea of this 
order, which are all terrestrial, and differ from the last in their 
respiratory organs. The male sexual organs are most fre- 
quently announced by the presence of linear or filiform ap- 
pendages, and sometimes of hooks, placed at the internal 
origin of the first subcaudal laminae. The females carry their 
eggs under the breast, &c. 
