A. EF. Verrill—Mollusca of the New England Coast. 261 
shells, but concentrically lined in the young. The surface is else- 
where covered with pretty regular and not very close, slightly 
elevated concentric lamelle, which are sometimes more or less 
reflexed at the anterior end, while on the posterior dorsal area they 
are thin, more elevated, nearly straight and divergent. There is no 
distinctly defined lunular area, nor any definite radiating ridges 
running from the beak to the anterior margin, though a very indis- 
tinct undulation may sometimes be detected. The ventral margin is 
pretty regularly curved and shows no indentation below the acute 
posterior tip. 
Amussium, sp. 
Amussium jenestratum Verrill, these Transactions, vol. v, p. 582 (non Forbes). 
Mr. W. H. Dall has called my attention to the fact that the Amer- 
ican specimens formerly referred by me to the species quoted are 
specifically distinct from the European types. I have been able to 
confirm this opinion by direct comparison of our shell with typical 
specimens sent to me by the Marquis de Monterosato. Our shell 
has a peculiar transverse striation on the hinge-margin not seen in 
the European specimens, and not more than two internal ribs, one on 
each side. The sculpture, also, is finer. 
Pecten pustulosus Verrill. 
Pecten Hoskynsi and var. pustulosus Verrill, these Transactions, vol. v, p. 581, pl. 42, 
figs. 22, 22a; pl. 44, fig. 11 (non P. Hoskynsi Forbes). 
By Mr. W. H. Dall, who has made a special study of the shells of 
this group, our American species is believed to be distinct from the 
typical Mediterranean form, with which he has been able to compare 
them directly. Although they are closely similar in form and exter- 
nal sculpture, our specimens differ in the hinge and in the absence of 
internal radiating ribs, characteristic of the genus Amusstum, and 
which are present in the true A. Hoskynsi. 
Possibly P. imbrifer Lovén may be identical with RP pustulosus, 
and not with A. Hoskynsi, to which it has been referred. In that 
case Lovén’s name would have priority. 
Pecten Clintonius Say. 
Pecten Clintonius Say, Journ. Acad. Nat. Sci. Phil. iv, p. 124, 1824, pl. 9, fig. 2. 
Pecten tenuicostatus Mighels, Proc. Bost. Soc. Nat. Hist., i, p. 49, 1841 (young). 
Pecten principoides Emmonds, Report N. C. Geol. Survey, 1858, p. 280, fig. 198. 
A comparison of specimens of this Miocene species, from Surrey, 
Va., with the more strongly ribbed, deep-water form hitherto 
