MICROCERAMUS. 157 



Orizaba, by the Academy expedition of 1890, is conic, with 

 8!/3 convex whorls, and measures 7 mni. long, 3.3 wide above 

 aperture. The whitish striag continue undiminished on the 

 last whorl, and are almost simple at the suture, which is 

 slightly and irregularly crenate in places, but without papillaB. 



An abundant supply of shells from Victoria, Tamaulipas, 

 and Diente, near Monterey, Neuvo Leon, is before me, pi. 26, 

 figs. 26, 27. These are corneous, not darker at the apex, and 

 clouded with lighter areas, which are produced by white 

 stria? on the corneous ground. There are also a few whitish 

 streaks. The surface is everywhere sculptured with delicate 

 thread-like rib-stria?, mostly white, sometimes slightly en- 

 larged at their lower ends, and either in pairs forming 

 papillae at the suture, with an unattached thread between 

 each pair, or with the papillaB almost obsolete, the suture 

 then being nearly simple. There are S 1 /^ to 9 whorls. Length 

 7.5, diam. 3.2 mm. 



This form is more conic than M. concisus, less cylindric; 

 and the striation of the later whorls is stronger and much 

 closer. The later whorls are more closely and distinctly 

 striate than M. texanus, and the shell is thinner. 



4. M. TEXANUS (Pilsbry). PI. 25, figs. 1, 2, 3, 4. 



Shell resembling M. gossei of Jamaica, but constantly 

 stouter in figure, decidedly less attenuated above. Sculpture 

 of thread-like oblique stride, finer and closer; sutural crenu- 

 lation more irregular on the lower whorls, and disposed to 

 be subobsolete. Whorls 9i/ 2 to 10i/ 2 . 



Length 10.5, diam. above aperture 3.5 mm. 



Length 8.66, diam. above aperture 3.5 mm. 



Length 8.5, diam. above aperture 3 mm. 



Southern-central Texas: San Marcos, Hays Co. (Pilsbry 

 and Ferriss) ; New Braunfels, Comal Co. ( J. A. Singley, Pils- 

 bry and Ferriss) ; Hondo River, north of Hondo, Medina Co. 

 (Pilsbry and Ferriss). 



Macroceramus gossei PFR. and BINNEY in part. M. pon- 

 tificus Gld., in part, STREBEL, Beitrag Fauna. Mex., etc., iv, 

 p. 90, at top of page, pi. 5, f. 4&. Macroceramus texanus 



