126 PALAEONTOLOGY OF CALIFORNIA. 



This is the first species of tins genus in which the callus of the lip has been 

 found to assume a falcate form. This peculiar character seems to ally the genus 

 to Aporrhais; but the constant thickness of the callus and the strombiform shape 

 of the shell will serve sufficiently to distinguish the two genera. 



TESSAROLAX, N. Gen. 



Shell fusiform, spire and aperture about equal; spire inerusted 

 by a thin deposit, so as to obliterate the sutures. Body whorl 

 bearing two (or more) varix-like processes. Aperture broad 

 above, continued below in a long, curved canal ; a posterior canal 

 continues for some distance up the spire. Columella inerusted, 

 but without folds or teeth. Outer lip produced into two long 

 spine-like canals. 



This very curious genus seems to combine the characters of several genera in 

 the family of the Strombidce. It has the dactylate lip of Pteroceras, the clavate 

 tubercles or varices of some of the species of true Strombus, the anterior and pos- 

 terior canals of Rostellaria, and the enveloped spire of Calypiraphorus. 



T. DISTORTA, 11. S. 

 PL 20, Fig. 82, and 82 a, b. 



Shell elongated; spire high; whorls five or six (from casts), 

 slightly convex in the middle, so as to produce a faint undulation 

 on the smooth surface of the spire. Apex usually flattened and 

 somewhat twisted ; at other times bluntly rounded. Surface of 

 body bicarinate, bearing on the upper carina, at a point about a 

 third of the circumference from the mouth, a short, clavate pro- 

 cess, abruptly truncated at the end and flattened on the sides. 

 On the lower carina is another process, flattened above and below, 

 prominent and angular at the extremity. This is placed about 

 half-way between the first and the outer lip. Aperture small, 

 broad above, rapidly narrowed and prolonged below into a canal, 

 which curves obliquely forwards and to the left. Above, the 

 mouth is continued into a canal, which runs beside the spire 

 for about two-thirds of its height, and then curves off obliquely 



