1906.] NATURAL SCIENCES OF PHILADELPHIA. 171 



Amnicola comalensis n. sp. Fig. 37. 



Shell distinctly perforate, ovate, thin, corneous, faintly marked 

 with growth -lines. Spire regularly conic, 

 the apex obtuse. Whorls 4^, regularly con- 

 vex, not shouldered, the suture w-ell im- 

 pressed. Aperture ovate, subangular above, 

 the peristome adnate for a short distance 

 above the perforation. 



Length 3.9, diam. 2, length of aperture 1.3 

 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, Fig. 37. 



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. 



CocMiopa riograndensis n. sp. PI. IX, figs. 10, 11, 12, 13. 



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 3^, 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 debris 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 debris 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 



