Geol.— Vol. II.] ANDERSON— CRETACEOUS DEPOSITS. 95 



lateral lobes, diminishing quite regularly in size from with- 

 out inward. On whorls of a diameter of 10.2 cm. there are 

 five of these lateral lobes which are unequally tripartite, so 

 much so, in fact, that they might almost as appropriately be 

 called unequally bipartite. The saddles are bifid, though 

 they have not the terminations shown in Gabb's figure. 

 Both lobes and saddles are moderately broad in their trunk 

 portions, the lobes regularly so; the terminations of the 

 lobes are digitiform, those of the saddles more or less 

 broadly scolloped. The involution of the whorls is more 

 than one-half and is, in one specimen, nearly two-thirds. 



Ocatrrence. — This species is found in abundance along 

 Cottonwood Creek, Shasta County, California, in the upper 

 portion of the Ilorsetown. It occurs also at Horsetown 

 itself. 



38. Desmoceras lecontei, sp. nov. 



Plate III, Figs. 94 and 95; Plate X, Fig. 190. 



Shell moderate in size, discoidal, flat, and rather involute; diameter of the 

 largest specimen found, 8.5 cm.; greatest thickness, 2.75 cm.; ratio of the 

 diameter of umbilicus to height of coil, 1:4; section of the whorl quadrate, 

 narrowing slightly toward the periphery; umbilicus narrow, but not deep, the 

 walls abrupt on each whorl, the inner coil forming a flattened ledge; ventral 

 surface rounded or slightly flattened; sides and surface of shell ornamented 

 with radiating, flexuous ribs which bifurcate a little above the middle of the 

 side on some specimens, and branch into three or more divisions on others; 

 ribs at first inclining forward, then backward, and finally forward upon 

 approaching the ventral region. In the more finely sculptured specimens of 

 this species the ribs are rather closely crowded together, while in others they 

 are as much as 2 mm. apart. Both ribs and interspaces are rounded. The 

 ribs do not continue across the ventral surface as a rule, but there are occa- 

 sional thickened ridges, probably of the nature of varices, upon this surface, 

 occupying the position of about each eighth or tenth rib. 



In Gabb's species, as figured in Pal. Cal., Vol. II, PI. XX, 

 the ratio of the width of umbilicus to height of coil is i : 3, 

 the umbilicus being relatively wider than in D. lecontei. 

 The figure shown in Pal. Cal., Vol. I, PI. X, has even a 

 wider umbilicus, and truthfully represents the specimen 

 from which it was drawn. In Gabb's species, furthermore, 

 the ribs are coarser, and the specimens do not show the 

 varices on the ventral surface, clearly seen in D. lecontei. 



