170 



PROCEEDINGS OF THE ACADEMY OF 



[Mavch, 



^^ 



Fig. 32. 



Fig 33. 



Fig. 34. 



Fig. 3' 



to insufficient food supply. Individuals are, however, very numerous. 

 Associated with them are numerous Physas, also of pygmy proportions, 

 though evidently adult. The snails of these springs evidently consti- 

 tute physiologic rather than morphologic varieties. 



AMNICOLID^ 

 Paludestrina seemanni (Ffld.). 



New Mexico: South Spring creek, near Roswell, in a Pleistocene 

 deposit (Cockerell and Tinsley, 1899). 



Texas: Drift debris of Pecos river, about a mile above the High 

 Bridge, Val Verde county (Pilsbry and Ferriss, 1903). 



Dr. R. E. C. Stearns has recorded this species from Death valley, 

 Inyo county, California. The specimens, some of which are before me,, 

 are somewhat more robust than those from New Mexico and Texas. 

 The above records largely increase the eastward range of the species. 



Paludestrina diaboli n. sp. Fig. 36. 



Shell very slender, turrite, shaped about like P. seemanni; composed 

 of 4^ very convex whorls separated by a deep suture. 

 Surface smooth. Aperture vertical, oval, a trifle nar- 

 rower above than below, but not angular there. Peris- 

 tome continuous, barely in contact with the preceding 

 w^horl for a short distance near the upper end. Umbili- 

 cus small but distinct. 



Length 1.3, diam. .62 mm. 



Drift debris of the Devil's river, about four miles from 

 its mouth, Val Verde county, Texas. A single shell was 

 also found on the Rio San Filipe near Del Rio, in the same county. 



The shells were all taken dead and bleached. It is readily separable 

 from P. seemanni by its diminutive size. This is the smallest species, 

 of its familv known from North America. 



Fig. 36. 



