CRETACEOUS PEEIOD. 203 



of nodes at each side of the dorsum. Saddles all broader, and simpler in 

 outline than the lobes ; none of the former being- really digitate, and those 

 near the ventral side of the volutions, especially the inner volutions, are 

 nearly as simple in outline as they are in Geratites. 



This shell presents some differences from the description by Dr. 

 Shumard of A. Swallovi, the principal of which is the absence of the nodes 

 at the umbilical side of the volutions and of the distinct transverse ribs of 

 the dorsum mentioned by him; but these are not regarded as essential 

 sjDecific characters. 



Full diameter of the shell, about eighteen centimeters; transverse 

 diameter of the aperture, nearly five and a half centimeters; long diameter 

 of the same, about eight and a half centimeters. 



Professor Hyatt writes me, after an examination of the specimen 

 figured on Plate XX, that he regards it as a species of his genus Btichiceras, 

 but that "it differs from B. Syriacum, the type of the genus, in having the 

 larger lobes and cells more Ammonite-like." 



Position and locality. — Strata of the Cretaceous period; Glendale, Long 

 Valley, Utah. 



Family TURRILITID^. 



Genus HELICOCERAS d'Oibiguy, 1842. 



Helicoceras Pariense White. 



Plate XIX, fig. 2 a, h, c, and d. 



Shell dexti'al; spire much depressed; whorls distinct, subchcular or 

 very broadly oval in transverse section, increasing somewhat rapidly in 

 size; surface marked by comparatively strong, rather abruptly-rounded 

 annidations, which cross the whorls obliquely; annulations only slightly 

 prominent upon the inner side of the whorls, but more prominent upon the 

 upper and under sides; upon the outer side of the whorl each annulation 

 bears a pair of prominent nodes, one on each side of the siphuncle, forming 

 two dorsal rows of nodes along the whole length of the shell, the portion 

 of the annulation between each pair of nodes being sti'aightened and 

 slightly flattened upon the beak. The annulations are apparently always 



