258 PALEONTOLOGY OF NEW JERSEY. 



the lobes or which are sinuses. There appear to have been three com- 

 pound divisions of the lobes so far as can be seen on the fragments, and 

 the principal sinuses seem to have been bilobed. The back of the shell 

 has been round and on one of the fragments is seen to be about three- 

 eighths of an inch thick, and the siphon correspondingly large. The dorsal 

 lobe has been quite small, with three compound digitations on each side, in 

 the only place in which it can be seen, and extends not more than a fourth 

 of an inch below the upper line crossing the dorsum; outside of this is a 

 short, slender, compound, secondary lobe which divides the large first 

 lateral sinus into two principal divisions. The next lobe is large and has 

 its branches extending below the sinus and upon the rounded dorsum of the 

 shell. The entire details of this lobe can not be made out, but I have 

 figured it as far as it exists, so it can be seen and compared with that of 

 A. placenta given, from which it will be seen to differ very materially; too 

 much to have been a part of an overgrown specimen of the same species. 



Formation and locality: There is no locality further than "N. J." given 

 with the specimens. They are from a hard, brown, highly ferruginous 

 sand, somewhat diff'erent from any specimens which I have before seen, 

 and I am inclined to thiidi they may have come from the iron nodules found 

 near the surface of the plastic clays. 



Ammonites (Sphenodiscus) lenticularis. 

 Plate XLi, Figs. 8, 9. 



Ammonites lenticularis Owen, 1853, Kept. U. S. Geol. Surv. Iowa, Wis., and Mis- 

 souri, p. 579, PL VIII, Fig. 5. 



Ammonites lobatus Tuomey, 1854, Proc. Acad. Nat. Sci., Phila., vol. 7, p. 168; 

 Meek and Hayden, ibid., vol. 8, p. 380; Gabb, Synopsis, pp. 13, 13; Meek, 

 Check List, p. 24 ; Geol. Surv. New Jersey, 1868, p. 730. 



Placenticeras {Sphenodiscus) lenticulare (Owen) Meek: Invert. Paleont. U. S. 

 Geol. Surv. Terr., vol. 9, p. 473. 



The above named species has been pretty generally recognized as a 

 New Jersey fossil, although I have been able to obtain only very small 

 fragment^ representing it, among all the collections to which I have had 

 access. These are, however, of so marked a character as to leave no ques- 

 tion of their identity. The fragments noticed consist, on^ of them, of casts 



