70 



THE NAUTILUS. 



the umbilicus. The ribs show a tendency to bifurcate from 

 these I'idge-Hke tubercules, and become less distinct on the sides 

 of the shell, curving gently backward, and becoming very dis- 

 tinct and wider near the outer margin where they turn decid- 

 edly forward. The suture line is simple, consisting of a few 

 broadly rounded saddles and wide lobes having very short 

 branches. Saddles little indented, and are bifid with rounded 

 denticles and incisions. Lobes unequally tripartite. 



Notes. This form easily distinguished from S. stantoni, as it 

 has nearly twice as many ribs, a lack of fine lines, striations on 

 ribs and interspaces, and a greater size. Named in honor of 

 Professor A. F. Rogers, Stanford University, Calif. 



Type. Museum, Stanford University, Calif. 



Locality. Three-quarters of a mile South of Carnegie, Corral 

 Hollow, Tesla Quadrangle. 



Horizon. Horsetown, middle Cretaceous. 



Chico — Upper Cretaceous. 

 Atafhrus pembertoni, n. s. Hall and Ambrose. 



Description. Shell medium, thick, rather flattened, spire low; 

 whorls four, rounded, enlarging rapidly anteriorly, and revolv- 

 ing a little obliquely; whole body being about twice as large as 

 penultimate. Aperture oblique, subcircular, columellar lip 

 thick and rather straight. Surface smooth, marked only by 

 occasional very faint lines of growth; umbilical region covered 

 by a smooth callus, which merges insensibly into general surface. 



Dimensions. Alt., 12 mm.; lat., 18 mm.; alt. of body whorl, 

 7 mm. ; alt. of aperture, 9 mm. 



Notes. Distinguished from A. crassa by its size, higher spire, 

 and non-rounding of columellar lip. Named in honor of J. R. 

 Pemberton. 



Type. Museum, Stanford University, California. 



Locality. Jordan Ranch, Arroyo del Valle, Tesla Quadrangle, 

 Alameda County. California. 



Horizon. Lower Chico, upper Cretaceous. 



Cerithium branneri, n. s. Hall and Ambrose. 

 Description. Shell elongate, slender; whorls numerous, prob- 



