Zoological Society* 153 



Museum. The specimens were brought under the notice of the 

 Meeting. 



The exhibition was resumed of the Shells collected by Mr. Cuming 

 on the western coast of South America and among the Islands of the 

 South Pacific Ocean. Those brought before the present Meeting 

 were accompanied by characters by Mr. G. B. Sowerby, and com- 

 prised the following species, the characters of which are given in the 

 f Proceedings.' 



Genus Hipponyx. " Of this remarkable genus Mr. Cuming brought 

 home three species in such perfect condition, as respects the shell, as 

 to possess both valves in situ. The two specimens which exhibit these 

 three species appear to me so interesting that I shall venture upon a 

 particular description of them. The first, of the species which I have 

 named Hipp. Mitrula, is a group of about twenty individuals, of va- 

 rious sizes, from V-u- to -£- an inch in diameter, adhering by their lower 

 or flat valves to an irregular piece of stone ; the attached valves as 

 usual, are conformed to the irregularities of the surface of the stone, 

 and when they have been at first attached to a cavity, they are hol- 

 low : the upper valves are also somewhat modified in form by the 

 same cause, so as to be more or less regular according as the lower 

 valve has adhered to a more or less smooth and even part of the 

 stone. The attached valves have not attained a great degree of 

 thickness, consequently I do not suppose any one of the individuals 

 to be of advanced age ; there are, however, several which can only 

 just have occupied their positions on the stone : these are not above 

 T V part of an inch in diameter, and they show the perfect point of 

 the upper valve, somewhat convoluted and inclined toward the ante- 

 rior edge. Other individuals, which are placed in a cavity of the 

 stone, are very regular in shape, but have their ridges slightly curved 

 upwards in conformity with the nearly regular vesicular shape of the 

 cavity. The edges of the lamella near the outer margin in most of 

 the specimens are furnished with a thin fringe of epidermis, but the 

 very young shells are destitute of this. An individual of Hipp, 

 subrufa is observable among the group of Hipp. Mitrula: its apex is 

 distinctly spiral and its epidermis hairy. 



" The second specimen belongs to the species which I have named 

 Hipp, barbata. This is a very complete specimen, and reminds me 

 of the beautiful fossil species Hipp. Cornucopia ; it is a small indivi- 

 dual, having its attached valve very much thickened and adhering to 

 a much larger one of the same species ; its edge is much elevated 

 and it is deeply concave ; the free valve is rather smaller, and coni- 

 cal, and its edge is surrounded by the elevated edge of the attached 

 valve."— G.B.S. 



Hipp. Mitrula (Pileopsis Mitrula, Lam. Patella Mitrula, Auct.), 

 subrufa (Pileopsis subrufus, Lam. Patella subrufa, Dillw.), radiata, 

 Gray, and barbata. 



Genus Mouretia. Mouret. Peruviana, stellata, and reticulata. 



Genus Siphonaria. Siph. costata, radiata (differs from Siph. 

 costata rather by its form than by any other character ; this being 



Third Series. Vol. 7. No, 38. Aug. 1335. X 



