218 BULLETIN OF THE 



and P. noronhensis Smith, differing from both in having more numerous ribs, 

 flatter and similar valves (the two valves are differently sculptured in the 

 others), and in details of form and sculpture of surface and ears. 



In one specimen, apparently quite adult, though not as large as one of the 

 dead valves, there are on the interior of the valves, especially the left one, 

 narrow lira) corresponding to grooves bounding the ribs externally, but which 

 are hidden on the .outside by the imbricated sculpture. These lira are very 

 distinct, and are raised at the ends into a little white prominence like the lira) 

 of ^. alaskensis; one more instance of the interchangeability of characters in 

 this group. 



The soft parts are streaked with purple in dots and dashes ; there is an 

 ocellus for each rib on the margin, except near the anal opening, where the 

 mantle margin is without them, and is folded in such a way as irresistibly to 

 suggest that it is the first step toward siphonation; there are here two very 

 peculiar large crimson color marks on the mantle edge not duplicated elsewhere. 

 The ocelli are of different sizes, some mucli larger than others. The remainder 

 of the superficial anatomy calls for no sjjecial remark. 



Pecten exasperatus Sowerbt. 

 Pecten exasperatus Shy., Thes. ConchyL, Pecten, p. 64, pi. xviii. figs. 183-186, 1846. 



Valves of j'oung specimens were found in 13-19 fms., Charlotte Harbor, 

 W. Florida, and in 640 fms., Yucatan Strait ; the latter fresh, but not original 

 to that depth, in all probability. 



Tliis species is very closely related to, if not identical with, P. fusco-purpureus 

 of Conrad, M'hich name would, if the species be identical, fall into synonymy. 



The adult hinge line in perfect examples usually shows the transverse corru- 

 gations (referred to imder species of Pseudaviusium) with great distinctness. 



Pecten ornatus Lamarck. 



Pecten ornatus Lam., An. s. Vert., VI. p. 176, 1819. 



Young specimens of this common West Indian species were obtained at 

 Station 11 in 37 fms., off Havana in 80-182 fms., on the western coast of 

 Florida in 50 fms., and a single valve, doubtless drifted but fresh, off Santa 

 Lucia, at Station 220, in 116 fms. 



Pecten antillarum Recluz. 

 P. antillarum Ee'cluz, Journ. de Conchy!., IV. p. 53, pi. v, fig. 1, 1853. 



Dead valves were found by Sigsbee off Havana, in 127 fms. 



This species lives in a few fathoms of water about the Florida Keys, where it 

 has been abundantly collected by Hemphill and others. The soft parts are 

 about the same color as the shell, the foot vermiform, simple, and quite small. 



