132 PALAEONTOLOGY OF CALIFORNIA. 



linear, and in the younger whorls obsolete. Between the highest 

 rib and the suture, on the shoulder of the whorl, is another 

 linear rib ; and below the one on the lower angle, and on the 

 inferior surface, are two or three smaller ribs and numerous 

 (about twenty) fine elevated lines. These are all crossed by 

 lines of growth which, on the sides, are only visible between the 

 ribs, where they form fine connecting bars. These lines show 

 that the lip was broadly emarginate on the outer side and sinuous 

 below, being most prominent on the columellar side of the 

 middle. 



Figures, natural size, and a magnified view of one volution. 

 Locality: North fork of Cotton wood Creek, Shasta County, and Orestimba 

 CaHon, Stanislaus County. 



T. SERIATIM-GRANULATA, Roem. 

 PL 20, Fig. 88. 



(? T. planilateris, Con. ; Emory's Rep. Mexican Boundary, p. 158, pi. 14, fig. 1.) 



(f T. irrorata, Con.; Proc. Acad. Nat. Sci. Phila., 1855, p. 268.) 



(T. seriatim-granulata, Roem.; Kreide von Texas, p. 39, pi. 4, fig. 12.) 



SHELL elongated; whorls numerous, sides flattened, upper and 

 lower margins very slightly bevelled, the lower most strongly so. 

 Mouth subquadrate. Surface marked by a variable number of 

 crenulate, or finely tuberculate, ribs; between these ribs are 

 fine, elevated lines, some of the largest of which are faintly un 

 dulated. 



Figures, natural size and magnified. 



Localities : Three specimens from Tuscan Springs, collected by Dr. Veatch ; also 

 found at Cottonwood Creek, Shasta County, and in the Siskiyou Mountains, Siski- 

 you County. 



No two of the specimens are ornamented exactly alike. The large ribs are four 

 and five in number, with from three to no intermediate ones. The number of the 

 latter varies on different whorls of the same specimen, and their arrangement 

 appears to follow no definite rule. 



These specimens being so variable, it is more than probable that the forms de 

 scribed from Texas by Roemer and Conrad, which are, at least, very closely allied, 

 and which only differ by the presence or absence of one or two ribs, and in no 



