MIOCENE MOLLUSCA AND CRUSTACEA. £5 



Family ANATINID^]. 



Genus PERIPLOMA Schumacher. 



Periploma(?) alta. 



Plate xvi, figs. 7 and 8. 



Periploma alta Conrad: Proc. Acad. Nat. Sci. Phil. 1862, p. 585; Cat. Mioc. Fossils; 



ibid., p. 572; Am. Jour. Conch., vol. 2, 1866, p. 70, PI. iv, figs 10; Meek, Check 



List Miocene Foss., p. 11. 

 Anatina alta (Con.) Heilprin: Mioc. Foss., New Jersey, Proc. Acad. Nat. Sci. Phil., 



pp. 397 and 403; Cont. Tert, Geol. and Pal. of the U. S., p. 8. 

 Compare Raeta alta Con.: Append, to Kerr's Rept., N. C, p. 19, PI. in, fig. 3. 



Mr. Conrad's description of this species in the Proceedings of the Acad- 

 emy of Natural Sciences, Philadelphia, is as follows: " Suborbicular, subin- 

 equilateral, anterior side subrostrated, and truncated, direct; basal margin 

 profoundly rounded medially and posteriorly ; anterior obliquely truncated 

 or very slightly emarginate. * * * A much larger species than P. (Ana- 

 tina) papyracea Say, but closely allied." In the American Journal of Con- 

 chology, as cited above, his description is somewhat different. He says of it: 

 " Obtusely ovate in the adult; substance thin; suborbicular when young; 

 posteriorly ventricose; anterior side subrostrated, compressed; the end 

 truncated, direct, much above the base line, which is profoundly rounded; 

 anterior submargin of the right valve with a slightly raised line, anterior 

 to which the valves are suddenly contracted." 



The first description corresponds much more nearly with the specimens 

 received from the Academy of Natural Sciences at Philadelphia, which are 

 supposed to be those used by Mr. Conrad, than does the second, and the 

 figure given with the later description in the American- Journal of Con- 

 chology does not at all correspond to the specimen from which it is supposed 

 to have been drawn. His later description was evidently drawn from the 

 young specimen figured by him at that time. The specimens are some- 

 what suborbicular in outline, and moderately convex, but extremely thin 

 and fragile in texture, while in the specimens in hand it is entirely impos- 

 sible to say if they have been inequivalve or not, as they are both so 

 crushed, in the only one showing both valves, as to render it uncertain. In 



