828 CRETACEOUS PALEONTOLOGY. 



tions of both lobes and saddles are more or less deeply bifid or 

 trifid. 



Remarks. — ^This species is the common, Scaphite of the Mer- 

 chantville clay. It is different from all other American 

 representatives of the genus- in the peculiar expansion of the 

 living' chamber to the geniculate bend beyond which it rapidly 

 contracts to the aperture. Whitfield's 5*. similis is evidently only 

 a young individual of S. hippocrepis. 



Formation and locality. — ^^Merchantville clay, near Matawan 

 (loi), near Jamesburg (139), Lenola (163). 



Sub-order PACHYCAMPYLL 

 Family SPHENODISOIDAB. 



Genus Sphenodiscus Meek. 



Sphenodiscus lobatus (Tuomey). 



Plate CVL, Figs. 1-2. 



1854. Ammonites lobata Tuomey, Proc. Acad. Nat. Sci. Phil.^ 



vol. 7, p. 168. 

 1861. Ammonites lobata Gabb, Synop. Moll. Cret. Form., p. 



69 (13)- 

 1864. Ammonites lobatus Meek, Check List Inv. Eoss. N. A., 



Cret. and Jur., p. 24. 

 1868. Ammonites lobaiius- Con., Cook's Geol. N. J., p. 730. 

 1892. Amm,onites (Sphenodiscus) lenticidaris Whitf., Pal. N, 



J., vol. 2 (Monog. U. S. G. S., vol. 18), p. 258, pi. 41, 



figs. 8-9. 

 1903. Sphenodiscus lobatws Hyatt, Monog. U. S. G. S., vol. 44, 



p. 66, pi. 6, figs. 1-2, pi. 7, figs. 1-2 pi. 9, figs. 11-13. 



Description. — Shell attaining a large size, large examples 

 having 9. diameter of 220 mm. or more ; compressed-lenticular in 

 form, the outer volutions almost completely embracing the inner, 

 leaving but a small or nearly closed umbilicus ; the sides of the 

 volutions smooth, gently convex from the umbilical to the ven- 



