154 PALAEONTOLOGY OF CALIFORNIA. 



very base of the Cretaceous. So much for ti priori reasoning, based on negative 

 grounds. 



From the Shasta Group, Colusa County, near the Hot Sulphur Springs. 



TRITONIUM, Link. 



T. CALIF.ORNICUM, n. s. 



PI. 26, Fig. 33. 



SHELL small, thin ; spire elevated, whorls seven and a half, the 

 first three and a half minute, nuclear, rounded and smooth ; the 

 others rounded and costate ; suture impressed, varices about two 

 to a volution, prominent. Aperture wide in the middle, acute 

 posteriorly, and narrowed and produced into a short canal 

 anteriorly ; outer lip acute on the margin, bearing a thickened, 

 rounded varix behind; inner lip slightly incrusted; canal abruptly 

 deflected, moderate in length. Surface ornamented by about 

 twenty acute longitudinal ribs, and about a dozen revolving ribs ; 

 between each pair of the latter are two or three fine elevated 

 striae ; where the first four of the larger revolving lines cross the 

 longitudinal ribs, at each point of intersection, is a minute 

 tubercle. 



Length, .7 inch ; length of aperture, .45 inch ; width of body whorl, 4 inch. 

 Kare in the Tejon Group, Tejon. Dr. Horn. 



S. Gen. TRACHYTRITON, Meek. 

 T. (T.) TEJONENSIS, n. s. 



PI. 26, Fig. 34. 



SHELL large, fusiform, thin, spire elevated; whorls four and a 

 half or five, subangulated, nodose. Aperture broad, anterior end ? ; 

 outer lip (? dentate or) plicate within, inner lip straight anteriorly; 

 body whorl flattened and sloping above, bearing about ten flat 

 tened tubercles on the angle, and with two or three larger and 

 numerous smaller revolving lines anteriorly. 



