CEPHALOPODA OF THE OEETAOEOtJS MARLS. 271 



situated on the inside of the coil; besides this, there are apparently three 

 principal lobes, situated, one on the line of the upper row of nodes, or 

 nearly opposite the siphon, and a larger one midway between it and the 

 siphon; the one on the upper side of the tube is much larger than that 

 below. There have also been secondary lobes between these primary ones. 

 The sinuses have been correspondingly large and of unequal size, but owing 

 to the wearing of the surface the details of structure can not be made out. 



This species differs very materially from any of those described from 

 the west, in the details of structure. It is perhaps more like H. Newtonij 

 Whitf., from the Black Hills of Dakota (see Paleont. of the Black Hills, 

 PL XV, Figs. 1-4) than any other, but it differs in being sinistrally coiled 

 instead of dextrally as that one is. F. B. Meek also figures a species in the 

 U. S. Geol. Surv. Terr., vol. 9, PI. xxi. Fig. 4, but without name, which 

 bears considerable resemblance to this one in surface detail. 



Formation and locality : According to Dr. Morton the type specimen was 

 found at Arneytown, New Jersey, by Mr. T. A. Conrad, and would conse- 

 quently be from the Lower Green Marls. The second specimen mentioned 

 above is to all appearances from the same place ; both of these are in the 

 Acad. Nat. Sci., Phila. The third example is from the same position at 

 Atlantic Highlands, New Jersey, and is in the collection at Columbia 

 College. 



Genus SOLENOCERAS Conrad. 



In the Jour. Acad. Nat. Sci., Philadelphia, 2d ser., vol. 4, p. 284, Mr. 

 Conrad proposed the above generic name as a division of D'Orbigny's 

 genus Ptyclioceras, using Dr. Morton's Hamites ammlifer as the basis for his 

 diagnosis. The shells of D'Orbigny's genus consist of a slender, tapering 

 tube, which, after attaining a certain length, is suddenly and abruptly returned 

 upon itself, the two portions being in close contact. Mr. Conrad supposed 

 that in the case of Hamites annulifer Morton the outer section, or larger 

 section, after having been returned upon the earlier part for a short distance 

 had again become deflected away from it at a considerable angle. I am not 

 aware that Dr. Morton's species is positively known by any other than the 

 type specimen, which is an internal cast of the outer chambers only, 

 although Mr. Conrad cites it as occurring in Alabama as well as in New 



