Log ax.] The Invertebrates, Benton Group. 477 



and, like the latter, deeply bifid, with sinuous and deeply digi- 

 tate margins ; first lateral lobe as wide as the siphonal lobe, but 

 somewhat shorter, and provided with two nearly equal, bifur- 

 cating and digitate terminal branches ; second lateral sinus not 

 more than half as long and little more than half as wide as the 

 first, and somewhat similarly divided and subdivided ; second 

 lateral lobe about half as long and wide as the first, but tripar- 

 tite at the extremity, the divisions being nearly equal and 

 digitate ; third lateral sinus small and merely provided with 

 two nearly equal terminal branches, with more or less sinuous 

 margins ; third lateral lobe hardly more than half as large as 

 the second, and bearing two very short terminal divisions. 

 Between the last-mentioned lobe and the umbilicus there is a 

 minute, trigitate lobe, very similar to the auxiliary lobe of the 

 third lateral sinus, but smaller. Length, eighty mm. ; height, 

 sixty-nine mm. ; convexity, forty-eight mm." 



Specimens belonging to this species occur somewhat abun- 

 dantly in the shales of the Septaria division of the Fort Benton 

 Cretaceous. They have been found in the upper Blue Hills 

 shales in the vicinity of Williams' Butte and in similar out- 

 crops on the Smoky Hill river. 



Scaphites mullananus M. &. H. Plate cv, figs. 2-4. 



Ammonites mullananus M. & H., 1862, Proc. Acad. Nat. Sci. Phil., p. 63. 

 ? A mrnonites mullananus Meek, 1876, U. S. Geol. Surv. Terr., vol. ix, p. 607, 



pi. viii, ff. la-c. 

 Scaphites mullananus Stanton, 1892, Bull. U. S. Geol. Surv. No. 106, p. 187, 



pi. xlv, ft. 2-4. 



Description : " Shell compressed subglobose ; rounded on the 

 border ; umbilicus small, deep, and acutely conical, between one- 

 third and one-half as wide as the breadth of the outer whorl 

 from the dorsal to the ventral side, showing about one-third of 

 each inner volution. Whorls increasing rather rapidly in size, 

 particularly in convexity, sloping on each side from near the 

 umbilicus toward the periphery, and rounding abruptly into 

 the umbilicus on the inner side, each of those within deeply 

 embraced by the succeeding turn. Aperture transversely reni- 

 form or sublunate. Surface ornamented by rather small, regu- 



