1889.] NATURAL SCIENCES OF PHILADELPHIA. 299 



THE AMERICAN SPECIES OF POLYPHEMOPSIS. 

 BY CHARLES R. KEYES. 



Portlock's generic term Polyphemopsis was introduced into the 

 literature of American Paleontology by Meek and Worthen, 1 who 

 referred to the genus the species described by Hall" in 1858 under 

 Bulimella, and also three additional forms, originally placed with 

 Loxonema and Eulima. A number of other American fossil gastero- 

 pods have from time to time been assigned to Portlock's genus. But 

 Polyphemopsis was founded on very imperfect material, and its 

 structural characters have never been sufficiently understood to 

 definitely limit the group. It seems to be regarded by the majority 

 of European writers as a synonym of Macrochitus Phillips. The 

 latter, however, has recently been shown to be identical with Solenis- 

 eu* Meek and Worthen, which has precedence over Phillips' pre- 

 occupied term. 



Although more than half a score of species have, in this country, 

 been referred to the genus, it is quite apparent that members of at 

 least two very different groups were included ; while a detailed com- 

 parison of the various representatives appears to indicate that, with 

 a few possible exceptions, no forms congeneric with Portlock's Poly- 

 phemopsis elongata, which may be regarded as the type of his genus, 

 have as vet been recognized, with any degree of certainty, in the 

 Paleozoic rocks of America. Until typical specimens of Poly- 

 phemopsis can be critically examined, the genus must be considered 

 as of very doubtful utility. 



As already stated there were embraced in this group such species 

 as constituted Hall's genus Bulimella. These perhaps best exemplify 

 the American forms of the section under consideration. The shells 

 are fusiform, with the spire elongated ; the whorls more or less 

 decidedly convex, the last rather large; the columella curved, 

 abbreviated or truncated at the base ; the inner lip often well denned 

 anteriorly, and usually separated from the outer by a more or less 

 well-marked notch ; surface smooth. Accordingly, this group would 

 include not only those forms originally comprehended under Buli- 

 mella but also the species hereafter enumerated, and perhaps a few 

 others now known under other generic titles. 



1 Geol. Sur. Illinois, vol. II, p. '67-. 



2 Trans. Albany Ins., vol. IV, pp. 29-30. 



