58 CRUSTACEA. 



Birgus, Leach, 



The tail is tolerably solid, suborbicular, and is furnished beneath 

 Avith two rows of laminiform appendages. The fourth feet are but a 

 little smaller than the two preceding ones; the two last are folded and 

 concealed, their extremities being received into a depression at the 

 bottom of the thorax; the fingers at the extremity, as well as those 

 of the penultimate pair, are hairy or spinous. The claws except- 

 ed, all the feet are visibly separated at their origin. The thorax 

 has the figure of a reversed heart, and is pointed anteriorly. 



It appears that from their size, the form of their tail, and the 

 more solid consistence of their teguments, the Birgi are unable to 

 shelter themselves in shells. They must retreat to holes, or fissures 

 in the rocks. 



The best known species, Cancer latro, L. , Herbst. XXI Vj 

 Rumph., Mus., IV; Seba, Thes., Ill, xxi, 1, 2, according to the 

 Indians, feeds on cocoa-nuts which it obtains during its noctur- 

 nal excursions for that purpose(l). In the others, or the 



Pagurus, Fab., 



The last four feet are much shorter than the preceding ones, and 

 the forceps are covered with granules. The tail is soft, long, cylin- 

 drical, narrowed near the extremity, and has usually but a single 

 row of filiform oviferous appendages. The thorax is ovoid or oblong. 



With the exception of some species domiciliated in sponges, Ser- 

 pulse and Alcyonii, they all inhabit univalve shells, whose aperture 

 they close with their anterior claws, and most frequently with one of 

 their fingers, which is usually larger than the other. It is asserted 

 that the female spawns twice or thrice in the year. 



Some species, C^enobita, Latr. ; distinguished from the others by 

 their projecting antennae, of which the mediate are nearly as long as 

 the external or lateral, and are furnished with elongated filaments, 

 whose thorax is ovoido-conical, narrow, elongated, strongly com- 

 pressed on the side, with the anterior cephalic portion shaped like 

 a heart, establish their domicil in terrestrial shells on rocks near 

 the sea, whence, at the approach of danger, they roll down with 

 them(2). 



(1) Pagurus laticauda, Cuv., Regn., Anim., IV, xii, 2; Desmar., Consider., p. 

 180, from the Isle of France. Very curious facts relating to the anatomy of the 

 preceding species have been published by M. Geoffrey Saint-Hilaire, from which, 

 however we do not draw similar conclusions. 



(2) Pagurus clypeatus, Fab.; Herbst., xii, 2. 



