154 PROCEEDINGS OF THE ACADEMY OF [March, 
Alt. 2.7,diam.5.25mm. 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 cronkhitet Newc., of northern California, ete., 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 (CkIl.). 
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 
+ 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, ete. 
In the Endodontide, where small differences in the shell characterize 
extensive series of species, it seems desirable to recognize as of generic 
value such readily recognizable 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. 
Radiodiscus millecostatus nu. sp. Fig. 10. 
Shell very small, disk-shaped, chestnut-brown, the first whorl bluish- 
white. Whorls 3?, 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 
