NO. 1483. 



UROCOPTID MOLL USKS—BARTSf'H. 



113 



ANISOSPIRA STREBELI Pfeffer. 



There are three specimens of this species in the collection, Cat. No. 

 162306, U.S.N.M., collected b}^ Godman at Cerro de Plumes, Oaxaca, 

 Mexico, 



Measurements of Anisosplra strebeli. 



DISSOTEOPIS, new subgenus. 



Exterior of decollated spire aj^Teeing with Anisosplra. Columella 

 provided with a strong spiral lamella which is situated a little above 

 the floor and a weaker twist or low fold posterior to this. Lamella in 

 the antepenultimate whorl cut b}^ a series of regularly spaced, oblique, 

 forward-slanting slits. 



Type. — Anisospira (Dlssot/'opis) stea7Visi, new species. 



ANISOSPIRA (DISSOTROPIS) STEARNSI, new species. 



Plate III, fig. 1. 



Shell subcylindric, milk white. Plug convex, covered on its inner 

 half bj rather large granules, outer half evenly, verj^ finely grauulose. 

 Exposed columella at the decollated end slightly sigmoid. Whorls 

 moderatel}^ convex, angular at the periphery which slightly overhangs 

 the summit of the succeeding whorls, marked by many ^er}" regular 

 and regularly spaced obliquely, slanting riblets which are about as 

 wide as the interspaces. There are about 120 riblets on the third to 

 last whorl. Peripher}'^ of the last whorl angular, the angle becoming- 

 less marked behind the outer lip. Base imperforate, very short, and 

 moderatel}" rounded at the junction of the columellar margin with the 

 preceding whorl, becoming gradually longer and more inflated from 

 there on to the peristome, marked by the continuation of the ril)lets, 

 which are somewhat flexed and thickened at the peripher}" and become 

 attenuated and very much crowded toward the umbilicus. Aperture 

 subcircular, bordered by a cord-like, white peristome, which has the 

 appearance on the inside as if it had been melted and flowed over the 

 adjoining wall; columellar folds visible in the aperture, but very weakly 

 developed at this point. In the interior the columelhi is slender, and 

 provided with a weak, median flexure, which extends throughout the 

 shell, and a strong, spiral lamella. The latter extends through the 

 last Ave whorls only and is largest in the penultimate whorl, tapering 



