172 PALjEONTOLOGY of ^NEW-YORK. 



222. 10. PLEUROTOMARIA SUBTILISTRIATA ( n. sp.). 



Pl. XXXVII. Figs. 5 a, ft, c, d. 



Lenticular ; spire much depressed ; volutions four or five, even, smooth, forming a verj' 

 depressed cone, with an elevation little more than one third the width of the shell ; aperture 

 transversely extended into a somewhat triangular form ; umbilicus very small ; surface 

 marked by fine close striae, which bend gently backwards on the upper half of the volution, 

 and more abruptly on the lower half, finally running almost parallel to the outer margin ; 

 outer margin of last volution sharply angular, with a mesial band parallel to the edge, 

 indicating the generic character of the shell. 



This species is much smaller and more depressed than either of the others, most of the 

 specimens being scarcely visible to the naked eye. The surface is apparently smooth, but 

 under a magnifier, is clearly marked by fine striae as described. The outer volution is 

 slightly concave near the margin, the others being plane. 



Fig. 5 a. View of the spire of a large specimen. 



Fig. 5 b. Profile of the same. 



Fig. 5 e, d. View of the spire and profile of the largest specimen seen. 



Position and locality. This species is known to me only as occurring in the concretionary 

 and irregularly bedded limestone, near the base of the Trenton limestone, at Watertown, 

 Jefferson county. 



223. 11. PLEUROTOMARIA LENTICULARIS. 



Pt.. XXXVII. Figs. 6 a, b, c, d. 



Trochxu lenticularu (?) Sowerbt in Sil. Researches, 1839, pag. 642, pi. 19, fig. 11. 



Pleurotomaria lenticularu, Conrad in MS. Emmons, Geol. Report, 1842, p. 392, f. 2; p. 393, f. 2 & 3. 



Compare Helieitet qualteriatus, Schujtheim, 1820, Petrefacta, p. 103 ; Id. Nachtrage, pi. 11, fig. 3. 



— obvallatus, Wahlenberg, 1821, Act. Soc. Sci. Upsal, Vol. viii. pag. 73, pi. 4, f. 1 &. 2, 



Solarium petropolitanum. Pander, 1830, Beitrage zur Geogn. Russland, pag. 150, pi. 1, fig. 3. 



Euomphalus pseudoqtialteriatui. Von Buck, 1830, Karst. Archiv, p. 156 - 158. 



Dtlphinula obvallata, Hisinger, 1831, Petrif. de la Suede, p. 8. 



Suomphalua qualteriatus, Goujfusb, 1834, in Kloden Verst. Brandenburg, p. 155. 



— — Bronn, 1835, Leth. Geognostica, pag. 94, pi. 2, fig. 1. 



— pteudoqualteriatut, Hisinger, 1837, Leth. Suecica, pag. 36, pi. 11, fig. S. 



— gualteriatut, Eschwald, 1840, Sil. Syst. in Esthland, p. 115. 



— — Gou>russ, 1844, Petref. Germanicm, Vol. iii. pag. 81, pi. 189, fig. 3 a, b. 



— — Vern-euii., 1845, Pal. Russia and the Ural Mountains, pag. 333, pi. 23, 



fig. 1 a, ft ; and var. A. fig. 2 a, ft. 

 Not Pleurotomaria lenticularis, Goldfdss, Petrefacta, Vol. iii. pag. 65, pi. 183, fig. 2. 



Lenticular ; spire depressed, subdiscoidal ; volutions scarcely four, flattened above, last 

 one obtusely angular at the margin and somewhat ventricose below ; aperture transversely 

 extended, subtrigonal ; umbilicus large, extending to the apex ; surface marked by fine 

 ■trite, which curve gently backwards from the suture, making an abrupt retral bend in 

 passing over the angles of the last volution. 



