14 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



Pyrgulopsis spinosus, sp. nov. 



(Plate II., Figs. 17-19.) 



Shell minute, imperforate, turreted, unicarinate, carina modified 

 into spinous processes on last three whorls, darker colored than 

 balance of shell; whorls 5-5^2, first two rounded, destitute of spines 

 or carina, the last three somewhat geniculate, angled at location 

 of carina, body-whorl large, sometimes with an occasional spine 

 below the carina; epidermis light horn color, nearly white at apex, 

 with microscopic longitudinal revolving striae, shining; aperture roundly 

 ovate, slightly longer than broad, rounded anteriorly; peristome not 

 continuous, sharp, simple, slightly reflected near the columella, sug- 

 gesting a faint umbilicus ; suture slightly impressed. 



Operculum spiral, reddish horn color. 



Specimen i. Length, 3.86"""; breadth, 2.34 mm . 

 2. 3.oo mm ; i.88 mm . 



j. 3.o6 mm ; 1.52""".' 



Habitat. Comal Creek, a clear stream at New Braunfels, Texas, 

 on rocky bottoms. It was associated with numerous specimens of 

 Goniobasis pleuristriata Say, Amnicola (species undetermined), and 

 Bythinella (species undetermined). 



In some particulars this form may be compared with Stimpson's 

 genus Potamopyrgus. It differs radically, however, in the character of 

 the spinous processes, which in that type are epidermal, while in our 

 form they are true testaceous products. It is the only spinous rissoid 

 described from the United States. 



Pyrgulopsis scalariformis Wolf. 



(Plate II., Fig-. 13.) 



Pyrgula scalariformis Wolf. Am. Jour. Conch., Vol. V., p. 198, Plate xvii., 

 Fig. 3 (1869). 



"Shell turreted, slender; whorls 6, chalky white; suture deeply im- 

 pressed; carinate its entire length on the lower edge of the whorls; 

 mouth small, ovate, but slightly connected with the last whorl. Length, 

 one-half inch. 



"Post-pliocene; abundant on the Tazewell shore of the Illinois 

 River." (Wolf.) 



No other locality has been recorded, and no living specimens have 

 ever been taken. The figure is a copy of the original, and has been 

 the main reliance in referring the species to this genus. We have not 

 been able to procure from the author either the types or authentic 

 specimens for examination. 



