I08 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



to the variety showing a median row of nodes upon the 

 abdominal surface, as shown in d'Orbigny's figures^ and 

 in some of Stoliczka's.^ 



Occurrence. — Acanthoccras corner essum is found in the 

 Lower Chico beds of the Santa Ana Mountains, Silverado 

 Canon, and at Bowers Canon, in Los Angeles County, 

 California. 



The type was obtained from the latter locality by Dr. 

 Stephen Bowers of Los Angeles. It is at present in the 

 collections of the University of California. 



54. Douvilliceras mamillare Schloth. 



Acanthoccras mamillare Schloth, Pal. Franc. Terr. Cretac, T. I, PI. 



LXXIII. 

 Acanthoccras mamillare (?) (Schloth) Stanton, Bui. Geol. Soc. Am., 



Vol. V, 1894, p. 445. 

 cf. Atnmonites mantelli (Sow.) Stoliczka, Pal. Ind., Vol. I, p. 81, PI. 



XLII, figs. I and la. 

 Ammonites stoliczkamis (?) Gabb, Pal. Cal., Vol. II, p. 135, PI. XXIII. 



In the upper Cretaceous beds of Clear Creek and the 

 Cottonwood Creek, Shasta County, California, this spe- 

 cies is somewhat common. It occurs here in beds evidently 

 quite similar to the Cenomanian, being found both in the 

 Lower Chico and the uppermost Horsetown. 



Among the collections at the University of California are 

 a number of specimens of AiJimonites mamillare from 

 France, and a comparison of these with several well pre- 

 served types from Shasta County shows few differences, 

 and the very strongest resemblances, between them. 

 There is the same general form and ornamentation ; the 

 same width and depth of umbilicus, and involution of 

 whorls; the tuberculation on both is identical, and goes 

 through a cycle of development the same in both cases. 



At a diameter of 2-3 centimeters (in the Shasta specimens) the ornamenta- 

 tion of the ribs consists of spinose tubercles in three rows. One of these 

 rows is upon tlie umbilical shoulder, one upon the ventral surface upon each 

 side of the median plane, and a third upon the middle of the side, where it 



1 Pal. Franc. Terr. Cret., I, PL CV. 



2 PaL Ind., VoL I, PL XXXIV. 



