CALLIOSTOMA. 367 



There are about 8 whorls, each one more or less markedly biangular 

 at the circumference, the lower augle obtuse, concealed bv the 

 suture on the spire, the upper one acute, continuing nearly to the 

 apex ; whorls concave above, slightly excavated around the pe- 

 riphery, a little convex beneath ; encircled by numerous unequal 

 spiral threads, the larger ones beaded, the smaller irregularly 

 crenated by rather decided incremental striae. Base radiatelv 

 striate, with about 8 to 12 smooth spirals, their interstices without 

 secondary riblets. Aperture oblique, rhomboi(iJfl ; columella heavy, 

 smooth, its face concave, obtusely subdentate at base. 

 Alt. 24, diam. 23 mill. 



Mazatlan ; Cape St. Lucas; fossil in post tertiary at San Ignacio 

 Lagoon. 



Tr. versicolor, Mexkic, Zeitschr f. Mai., 18-30, p. 172. — Carpenter, 

 Mazatlan Cat., p. 231.— T. exi;mius Reeve, P. Z. S. 1842, p. 185; 

 Conch. Byst. ii, p. 165, t. 208, £ 12. — Zizyphinus e.vimius Reeve, 

 Conch. Icon., f. 25 (1863). — T. eximius Rve., Philippi, ConchyL 

 Cab., p. 218, t. 32, f. 9.— Fischer, Coq. Viv., p. 196, t. 64, f. 1 ; 

 And of most American authors. — (?) Zizyphinus Californicus A. Ad. 

 P. Z. S. 1851, p. 168.— T. ceratus Fischer, ms. Coq. Viv., p. 333. 



Reeve gives Panama for locality. None of the shells before me 

 come from south of Mazatlan. The species is more obviously 

 bicarinate than C. lima, far less granulose, and with different base- 

 sculpture. C. ■palmeri Dall is allied, but more granulose, with 

 differently colored, more excavated columella. 



C. ADSPERSUM (Beck) Philippi. PI. 18, figs. 1, 2. 



Shell conical, imperforate, whitish-gray, flammulate with rufous, 

 encircled by delicate granulate threads ; whorls plane, angulated a 

 little above the sutures, the last biangulate ; base a little convex, 

 with 9 to 10 concentric, little elevated smooth lir?e ; aperture rhom- 

 boidal, angles rounded ; columella oblique, cylindrical, subdentate 

 at base. (Phil.) 



The shell is pretty solid, exactly conical. The whorls are even, 

 with a sharp carina close above the lower suture ; the last whorl 

 showing beneath this one a second rounded carina, bounding the 

 base. The sculpture of the upper surface consists of fine thread-like 

 or hair-like granulate spirals. I count five of them, the last forming 

 the sharp carina over the suture ; in the interstices there are finer 

 granulose lines. The base shows smooth, little-raised concentric 



