1916.] NATURAL SCIENCES OF PHILADELPHIA. 343 



All figures were drawn with an Abbe camera lucida. 



In these Proceedings for 1905, p. 271, a grouping of the species 

 of Oreohelix according to the characters of the genitalia was tenta- 

 tively advanced. The examination of many more species and local 

 races in the main confirms the arrangement then proposed. By the 

 genitalia the species group as follows. 



1. Epiphallus about as long as the penis, the retractor muscle inserted 



upon it; internally plicate part of the penis very short; 

 animal oviparous, etc. Subgenus Radiocentrum. 



2. Epiphallus much shorter than the penis, the retractor muscle 



inserted upon both at their junction (except in 0. barbatd); 

 internally plicate part of the penis \ to over \ of its length; 

 viviparous species. Subgenus Oreohelix. 



a. Penis long, the distal part about equal in diameter to the 



lower part, though usually collapsing on account of the 

 thinner walls. 0. strigosa, peripherica, hendersoni, elrodi, 

 haydeni and their varieties. Also 0. cooperi, which is 

 somewhat intermediate between groups a and b, being a 

 generalized species in genitalia. 



b. Penis short, the basal part decidedly more swollen than the 



distal, 0. yavapai, concentrica, metcalfei, pilsbryi, barbata, 

 and their varieties. 



The division of Oreohelix into "transversely ribbed," "smooth or 

 striate," and "longitudinally ribbed" groups by Hemphill and 

 Binney is a division of convenience in the identification of specimens, 

 but it has no relation to the affinities of the species. 



Teeth of Oreohelix. 



In Oreohelix there are two types of teeth, as W. G. Binney first 

 pointed out. In one group the central and inner lateral teeth have 

 no side-cusps or cutting points. Here belong: 



0. strigosa (Gld.). Binnev, T. M. vol. V, PI. IV, fig. h. 3 



0. cooperi (W. G. B.). Binney, T. M. vol. V, PI. IV, fig. g, and 



several examined by myself. 

 0. haydeni (Gabb). Binney, T. M. vol. V, PI. XVI, fig. b. Also 



0. h. betheli and 0. h. corrugata examined by myself. 

 0. peripherica (Anc). Binney, T. M. vol. V, PI. XVI, fig. a (var. 



newcombi). Also numerous radulse of several forms examined 



by me, from Henderson and Daniel's Stations 29, 30, 33, 36. 



3 Just what race of strigosa Binney had remains in doubt. In the same volume 

 he described and figured the genitalia of a Salmon River strigosa, which would 

 presumably be 0. s. jugalis, but perhaps O. s. subcarinata. He gives the formula 

 50-1-50 for a transverse row of teeth. As all the other species of Oreohelix exam- 

 ined by Binney and the writer have between 20-1-20 and 33-1-33 teeth, this 

 count is remarkable, and if confirmed would certainly indicate a species distinct, 

 from any other of which the dentition is known. 



