NO. 1483. 



VROCOPTID MOLL VSKS—BARTSCH. 



121 



EPIROBIA COAHUILENSIS, new species. 

 Plate IV, fig. 8. 



Shell small, subulate-conic, lig-ht horn yellow. Nuclear whorls 

 three, moderately inflated, smooth, forming- a cylindrical tip. Suc- 

 ceedino- whorls very low between the sutures, moderately rounded, 

 ornamented hy many, very regular and regularly spaced, decidedly sig- 

 moid, thread-like riblets, which are about one-half as wide as the 

 spaces that separate them. I counted tifteen in the space of 1 milli- 

 meter. The sigmoid curve of the riblets is better expressed on the 

 later whorls than on the early ones. Some of the riblets are white 

 and this lends the spire a somewhat mottled apY)earance. Sutures well 

 impressed. Periphery of the last whorl decidedly angfular, base v^ery 

 short, almost flattened, widely umbilicated, marked by the contin- 

 uations of the ribs, which extend into the umbilicus. Last whorl 

 shortly free, having the parietal wall of the aperture projecting for a 

 short distance bej^ond the penultimate whorl. (Aperture fractured 

 in the type.) Internal column without twist or fold, large, fully one- 

 third the width of the entire shell, thin, translucent, concave in the 

 center of each whorl, broadening- toward both ends, crossed by rather 

 distant, thread-like, axial riblets. 



The two specimens in the U. S. National Museum collection, Cat. No. 

 187505, were collected by E. W. Nelson in the Sierra Guadalupe, 

 Coahuila, Mexico. They are not quite adult and it is possible that 

 full}' adult specimens may show less of the umbilicus, or may have 

 it completely closed, as in the other known Epirobia. The free last 

 whorl of the type, however, arg-ues against this. 



Measuninenls of Epirobia coahuilensis. 



a Type. 



PROPILSBRYA, new subgenus. 



Exterior of shell, like Epirobia. Internal column slender, hollow 

 throughout, having a somewhat submedian thread-like fold, which 

 extends over the entire length of the axis. In several of the whorls 

 preceding the last, this fold becomes very much enlarged, forming a 

 strong, spiral lamella. The parietal wall is furnished with a narrow 

 band-like lamella, which is pendant from the roof, and extends 

 throughout the spire; in the three whorls preceding the penultimate, 



