lOO CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Sek. 



44. Desmoceras voyi, sp. nov. 

 Plate III, Figs. 89-90. 



In the collections of the University of California are 

 three specimens of a Desmoceras, each of a diameter of 

 about 5 cm., two of which belong to the " Voy collection," 

 and are labeled "Cottonwood"; the third is from the 

 North Fork of Cottonwood, near Ono, Shasta County, 

 California, where it was obtained by the writer. 



The general form is discoidal, though somewhat inflated; thickness of the 

 specimens, about 2.5 cm., umbilicus narrow and deep, rounded on the 

 ventral surface, toward which the sides gently converge; surface marked by 

 many fine lines of growth which are flexuous and parallel to the six trans- 

 verse grooves. These grooves are bordered behind by a ridge upon the 

 shell, while they themselves are to be seen only, or ordinarily, upon the 

 cast. The ridges become more prominent upon the periphery, where they 

 bend strongly forward, forming a projection at the border of the aperture. 

 The section of the whorl is elliptical in specimens of this diameter, though in 

 the younger shells it is more nearly circular. The involution is deep, em- 

 bracing more than tliree-fourths of the preceding whorl. The suture is a 

 true Desmoceras suture, similar to that represented by d'Orbigny ' for Am- 

 viofiites lalidorsatus, to which this species seems to be related. The sec- 

 tional aspect, however, of Z>. voyi is much narrower than that of d'Orbigny's 

 figures. There are also some resemblances between this species and 

 D.jugalis Gabb;^ yet the differences will be seen to be greater than could 

 be admissible for an identity without unusual evidence. 



Occurrence. — Desmoceras voyi belongs to the lower or 

 central portion of the Horsetown beds of the Cottonwood 

 section. Ammonites latidorsaUis Mich, is a species be- 

 longing to the Gault, though it has also been found in the 

 Ootatoor beds of Southern India, which are thought to be 

 of Cenomanian age. 



45. Desmoceras ashlandicum, sp. nov. 



Plate IV, Figs. 107-109; Plate X, Fig. 196. 



Shell discoidal, compressed, not small, moderately involute, and coarsely 

 ribbed; section of the whorl elliptical, narrowing gradually toward the 

 periphery; umbilicus moderately large, and increasing more rapidly with 



iPal. Franc, VoL I, PL LXXX. 



s PaL CaL, VoL II, PL XXII, figs. 12, 12a and \ib. 



