180 CLASS CRUSTACEA. 



antennae presents an appendage or projection proceeding into 

 a point, or in the form of a spine. 



These Crustacea, which the Greeks name carcinion, and 

 the Latins cancelli, live for the most part in univalve and 

 empty shells. Their tail {Birgus excepted) presents, and in 

 the females only, but three false feet, situated on one of the 

 sides, and divided, each, into two filiform and hairy branches. 

 The three last segments are suddenly more naiTow. 



In some, such as 



Birgus, Leach, 



The tail is tolerably solid, suborbicular, with two ranks of ap- 

 pendages, in the form of laminae, underneath. The fourth 

 feet are only a little smaller than the two preceding ; the two 

 last are folded and concealed, their extremity lodging in a 

 depression of the base of the thorax. The fingers of the end, 

 as well as those of the last pair but one, are simply hairy or 

 spinous. With the exception of the claws, all the feet are 

 separated at their origin by a verj'^ sensible interval. The 

 thorax is in the form of an inverted heart, and pointed in 

 front. {Cancer latro, Linn.) 



Pagurus, Fal. 



The last four feet are much shorter than the preceding, 

 with the forceps charged with small grains. The tail is soft, 

 long, cylindrical, narrowed towards the end, and usually pre- 

 sents but one rank of oviferous appendages, and which are in 

 the form of a thread. The thorax is ovo'id or oblong. 



Some species, Ccenohita, Latr., are distinguished from 

 the others by their advanced antennae, and the middle ones 

 are almost as long as the exterior or lateral, and have elon- 

 gated threads. The thorax is ovo'ido-conical, narrow, elon- 

 gated, very much compressed laterally, and with the anterior 



