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 lirze corresponding to grooves bounding the ribs externally, but which 
are hidden on the outside by the imbricated sculpture. These lire are very 
distinct, and are raised at the ends into a little white prominence like the lirz 
of A. 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 much larger than others. The remainder 
of the superficial anatomy calls for no special remark. 
Pecten exasperatus Sowersy. 
Pecten exasperatus Sby., Thes. Conchyl., Pecten, p. 54, pl. xviii. figs. 183-186, 1846. 
Valves of young 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. 
This species is very closely related to, if not identical with, P. fusco-purpureus 
of Conrad, which 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 under species of Pseudamusium) 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 Réctivz. 
P. antillarum Récluz, Journ. de Conchyl., IV. p. 53, pl. 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. 
