154 PALAEONTOLOGY OF CALIFORNIA. 



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

 grounds. 



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



TRITONIUM, Link. 

 T. Californicum, n. s. 



PI. 26, Fig. 33. 



Shell small, thin ; spire elevated, whoi-ls 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. 

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



& Gen. TRACHYTRITOK, 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. 



