134 PROCEEDINGS OP THE ACADEMY OP 



DESCRIPTIONS OF NEW FOSSILS.* 

 Ptychoceras Mortoni. 



Shell small and thin, elongate cylindrical ; larger half, or body, very slightly 

 tapering, apparently rounded on the dorsum, and concave along the inner side 

 for the reception of the slender smaller half. Surface ornamented by rather strong 

 annular costae, which are less prominent, and somewhat irregularly divided on 

 the body, and bifurcate occasionally on the smaller part ; dorsum of the slender 

 half ornamented by two rows of very small nodes, arranged upon the costae ; 

 fine indistinct lines of growth mark the shell parallel to the ribs. Aperture, 

 septa, and siphuncle unknown. Length (of specimen imperfect at the aperture, 

 and apex of smaller portion) about 1 inch; breadth -26 inch ; diameter of slen- 

 der part -12 inch ; do. of body -17 inch. 



This shell is about the size, and has much the general appearance of a 

 species described by Dr. Morton from the deep cut of the Chesapeake and Dela- 

 ware canal, under the name of Hamites annuUfer (Jour. Acad. Nat. Sci. vol. 8, 

 pi. xi. fig. 4,; but differs from his figure in having bifurcating instead of 

 simple costae. It is possible, however, that they may not be distinct, though 

 it is hardly probable so important a character as the bifurcation of the costae 

 would have escaped the attention of so close an observer as Dr. Morton. 



Judging from the nodes seen along the dorsum of the smaller portion of our 

 shell, it appears probable similar or stronger nodes may have existed along the 

 outside of the body, or larger half; if so, it must have differed materially in 

 this respect from Dr. Morton's species. When entire our specimen must have 

 been not less than 1 J to 2 inches in length. 



Dedicated to the lamented Dr. George Morton of Philadelphia. 



Locality and position. Great bend of the Missouri, formation No. 4. of the 

 series. 



Serpula? tenuicarinatds. 



Shell growing in groups, or rarely single, slightly compressed-cylindrical, 

 increasing very gradually in size, irregularly curved or flexuous, not spirally 

 coiled; attached by one side nearly the whole length; having a distinctly 

 elevated, linear carina along the upper side ; surface sometimes very obscurely 

 undulating transversely, otherwise smooth. Length unknown; transverse 

 diameter about .14 inch. 



As we have no perfect specimens of this fossil, it is with some doubt we 

 refer it to the genus Serpula. It appears to have no internal septa as in Ver- 

 ■meius ; and we have seen no indications of an operculum as in Vermicularia ; 

 consequently we place it provisionally in the genus Serpula. 



Locality and position. — Mouth of Vermillion River, on the Missouri, formation 

 No. 2 of the series. 



VlTRINA OBLIQUA. 



Shell obliquely oval ; spire much depressed ; volutions four to four and a 

 half, first two or three increasing rather slowly in size, last one ventricose and 

 rapidly enlarging, prominent below ; suture distinct ; aperture circular ; surface 

 unknown. Greatest transverse diameter .64 inch ; height .50 ; diameter of 

 aperture .ST inch. 



Having seen only internal casts of this shell, we are in some doubt about its 

 generic relations ; as its associates, however, belong to land and freshwater 

 genera, and its form agrees very nearly with that of Vitrina, we place it pro- 

 visionally in that genus. It resembles a species described by Reuss and Von 

 Meyer, under the name of V. intermedia from the Tertiary Lacustrine deposits 

 in the north of Bohemia, (see Tert. Siiss. pi. 1 fig.) but has more volutions. 



Locality and position. Mouth Judith River, bed E of the section of freshwater 

 and estuary deposits at that place. 



* lllustrationg to be published hereafter in Lieut. Warren's Report. 



[May, 



