154 PROCEEDINGS OF THE ACADEMY OF [March, 



Alt. 2.7, diam. 5.25 mm. Type locality, Fairmount Park, Philadelphia, 

 near "Strawberry Mansion," No. 68,899, A. N. S. P., collected by E. G. 

 Vanatta. 



In my opinion the widespread Eastern race is not specifically dis- 

 tinct from Helix cronkhitei Newc, of northern California, etc., of which 

 specimens from Dr. Newcomb are before me, but it evidently requires 

 separation as a subspecies. 



Arizona: Chiricahua mountains, Cochise county, at Fort Bowie, 

 Bear Park and Cave creek canyon (Ferriss); Carr canyon, Huachuca 

 mountains (H. Skinner). 



New Mexico: Drift of Pecos river at Pecos (Ckll.). 



Texas : In 1885 I dug a single specimen of this species from the bank 

 of Comal creek, New Braunfels, where it occurred with several other 

 land and fresh-water shells. Singley reports it from the Pleistocene 

 of Swisher county. It is not known to occur living in Texas, or any- 

 where in the Austroriparian zone. Its occurrence in the Texan Pleisto- 

 cene is anomalous, like the presence of Pupilla blandi at New Braunfels. 



RADIODISCUS Pilsbry, n. gen. 



Minute, discoidal, openly umbilicate Patuloid snails with the first 

 1^ whorls minutely engraved spirally, the rest of the shell densely radi- 

 ally costulate; aperture lunate, but slightly oblique and as high as 

 wide. Type, R. millecostatus. 



This genus is proposed for a group of tiny Pyramidula-like snails, 

 various members of which have been found in Arizona, Mexico and 

 South America as far south as Patagonia. In the spiral sculpture of 

 the embryonic whorls these shells are like Helicodiscus ; in shape and 

 size they resemble Planogyra, but in that the embryonic shell is smooth. 

 There are also some similar Polynesian forms, referred to Charopa, etc. 



In the Endodontidce, where small differences in the shell characterize 

 extensive series of species, it seems desirable to recognize as of generic 

 value such readily recognizaljle groups as Radiodiscus. The species 

 are chiefly distinguished by their dimensions and the degree of fineness 

 of the sculpture. There are several undescribed forms in the collection 

 of the Academy. 

 Eadiodiscus millecostatus n. sp. Fig. 10. 



Shell very small, disk-shaped, chestnut-brown, the first whorl bluish- 

 white. Whorls 3f , slowly widening, separated by a very deep, chan- 

 nelled suture. The first whorl projects a little, and is microscopically 

 striate spirally, the rest of the whorls are radially very densely costu- 

 late, the riblets nearly straight, delicate and much narrower than 



