CRETACEOUS FOSSILS. 61 



one being the highest ; between these ridges are broad, concave, 

 shallow grooves. 



Septum composed of a dorsal, two lateral and a ventral lobe. 

 The dorsal saddle at its top is broader than the dorsal lobe, and 

 is deeply divided in the middle. The superior lateral lobe is 

 largest. Lateral saddle about as wide as the superior lateral lobe, 

 and is not bifurcated. Further details unknown. 



Figures, natural size. 



Presented to the Geological Survey by a gentleman at Battle Creek, Tehama 

 County, and said to have come from that vicinity. 



This shell is of the style of A. Leonensis, Con., but can be distinguished by the 

 proportionately narrower whorls and the presence of three well-marked ridges on 

 the dorsum, instead of the single one of that species. It is one of the handsomest 

 species in the State. 



A. NEWBERRYANUS. 



* 



PI. 10, Figs. 5, 6, and 6 a, b; also, PI. 27, Fig. 199, a, b, c. 

 (A. Newbemyanus, Meek. Trans. Albany Institute, vol. 4, p. 47.) 



THE specimens represented by Figures 5, 6 a, b, and c. correspond in the main 

 with the form described by Mr. Meek from Vancouver Island, under the above 

 name. The principal points of difference are in the ribs not being so definite as 

 described by Meek, and in the absence of the umbilical row of nodes. 



By a careful comparison of these specimens with one nearly seven inches in 

 diameter, obtained by myself on Vancouver Island in the fall of 1863, I find no 

 differences, except such as can be fully accounted for by the difference in age. 



This specimen, much larger than the one originally described, also shows some 

 other characters. It is figured on PI. 27, Fig. 199, a, b, c. The whorls are thicker 

 transversely, the umbilical margin is rounded, and the costse are, proportionally, 

 very much smaller, being barely more than a quarter as wide as the interspaces. 



Another peculiar character, not heretofore mentioned, is a minute pustular 

 roughening of the external surface, producing an appearance not unlike that 

 caused by the spine tubercles of some of the Spatcmgidce. These pustules are 

 small, scattered, and the surface between them is somewhat roughened. 



The periodical constrictions mentioned by Mr. Meek are not visible on all of 

 the California specimens, and when they do occur, are not always regularly 

 placed. On the large Vancouver Island specimen they are entirely wanting. 



Figures, natural size. Fig. G b, is from a specimen but little over an inch in 

 diameter. 



Localities: Comax ("Koomooks" of Meek), Vancouver Island; north fork of 



