94 PALAEONTOLOGY OF CALIFORNIA. 



sinus broad, rounded, and shallow. Surface marked by small, 

 curved, longitudinal ribs, running parallel with the outline of the 

 outer lip, most prominent a little below the suture, obsolete in 

 advance, and placed close together ; there are about from thir 

 teen to fifteen of these ribs to a volution, and they are crossed by 

 fine, revolving stride. 



Figure, slightly magnified. 



Locality: Near Fort Tejon ; Dr. Horn. 



The discovery of this shell in the Cretaceous Formation is interesting, inasmuch 

 as it carries the origin of the genus one formation lower than was heretofore 

 known. As might be expected in the oldest known species, the generic characters 

 are not as strongly marked as they are in the Tertiary forms. The folds on the 

 columella are small, very oblique, broad, and not prominent ; showing an ap 

 proach to the plain columella of the true Turris. 



TRITONIUM, Link. 



Triton, Montf. 



T. HORNII, n. s. 



PI. 28, Fig. 208. 



SHELL robust, fusiform ; spire high, whorls seven, angular, and 

 sloping above. Aperture elongated, broad, and biangular above ; 

 columella but slightly incrusted ; canal gently curved. Surface 

 marked by an irregular number of rows of tubercles ; sometimes 

 there is but a single row on the upper angle of the whorl ; in 

 other specimens there are three rows, more or less distinctly con 

 nected by longitudinal ribs; these are crossed by prominent 

 revolving lines. Varices prominent, not numerous. The elevated 

 apex and angular form, as well as the prominent tubercles, will 

 at once distinguish this from either of the following species. 



Fig. 208, magnified to about twice the size of the specimen. Some fragments 

 before me, however, indicate that the species sometimes attains a size even greater 

 than the figure. 



Localities: Not rare at Alizos Creek, near Fort Tejon ; and a single specimen 

 was found at Cochran's, near Mount Diablo (Division B.). 



