11 



of E-ist Looe, to whom our museum is indebted for muck 

 valuable assistance, presented to me the feather already re- 

 ferred to when speaking of the last species: — on which, 

 along the stem of the vane, were several specimens of this 

 species, standing in clumps, and of about their full growth. 

 It is clear that they must have seized on this feather, as well 

 as on the piece of cork when floating on the surface ; and 

 that in their first existence they are singly dotted over the 

 surface. Their clustering afterwards is in the way of pul- 

 lulation; and though closely set in the bottom, their 

 subsequent growth, is in every imaginable angle of direction. 



POLLICIPES. 

 GENERIC CHARACTER. The shell compressed at the 



sides, many valved, the plates rather contiguous, unequal; 



in number 13, or more; the lower side valves smallest. 

 * P. SCALPELLUM. Lepas S. Turt. Lin. Mont. Test. 



Brit., vol. 1, p. 18, pi. 1, fig. 3. Stew. Elem., vol.2, 



p. 365. 



This species has been described as scarce ; but I have 

 found it common, if not abundant. It is found on the branches 

 of Gorgonia Verrucosa, and Dynamena Filicula, two species 

 of Corals; and somewhat less frequently, but of greater size, 

 on the stone to which they are attached ; but in every case, 

 it stands erect, and singly, without clustering. 



CLASS III. 



CONCHIFERA . 



The shell always bivalve, wholly or partly covering the 

 animal ; sometimes free, sometimes fixed ; the valves mostly 

 joined at the margin by a hinge or ligament. The shell is 

 sometimes enlarged by testaceous or accessary pieces, not 

 belonging to the valves. 



This class is divided into two orders : Conchilera bimus- 

 culosa, and C. Unimusculosa. 



ORDER I. 



CONCHIFERA BIMUSCULOSA : 

 So named from having, in the interior, two separate and 

 lateral muscular impressions. It is divided into four sec- 

 tions : C. Crassipeda ; C. Tenuipeda ; (J. Lamellipeda ; and 

 C. Ambigua, or the Chamacea. 



