1906.] NATURAL SCIENCES OF PHILADELPHIA. 171 
Amnicola comalensis 0. sp. Fig. 37. 
Shell distinctly perforate, ovate, thin, corneous, faintly marked 
with growth-lines. Spire regularly conic, 
the apex obtuse. Whorls 44, regularly con- 
vex, not shouldered, the suture well im- 
pressed. Aperture ovate, subangular above, 
the peristome adnate for a short distance 
above the perforation. 
Length 3.9, diam. 2, length of aperture 1.5 
mm. 
Comal creek, near New Braunfels, Comal 
county, Texas. Also from the Guadalupe 
river about four miles above New Braunfels. 
This species is much smaller than A. limosa, 
decisa, or other forms resembling it in color 
and shape. A. cincinnatiensis Anth. and the very closely related A. 
peracuta P. and W. both have more shouldered whorls, and are much 
larger than A. comalensis. 
Cochliopa riograndensis 0. sp. Pl. IX, figs. 10, 11, 12, 18. 
Shell of the usual depressed-turbinate shape, openly umbilicate, of 
a slightly olivaceous corneous tint. Surface faintly marked with 
growth-lines, and sculptured with unequal spiral threads, a few of the 
larger ones dark colored. One thread at the shoulder is usually the 
most prominent. In some shells the spirals are very weak, hardly 
perceptible. Whorls 33, moderately convex, flattened and sloping 
below the suture, elsewhere rounded. Aperture quite oblique, rotundly 
ovate, the peristome thin, equably arched except near the outer and 
columellar insertions where it is noticeably straightened. The ends 
are connected across the parietal wall by a thin or thick callus. The 
columella is not noticeably thickened. 
Alt. 2, diam. 2.8 mm. 
Alt. 1.65, diam. 2.65 mm. 
Found in drift débris of Rio San Filipe near the Rio Grande, Val 
Verde county, Texas, thirty-six specimens. Pilsbry and Ferriss, 
1903. Types, 91,324, A.N.S. Phila. A single shell was also picked 
out of similar débris on the Devil’s river, about four miles from the Rio 
Grande, in the same county. 
This discovery of this form adds a new genus to the fauna of the 
United States and greatly extends the distribution of the group, the 
