1916.] NATURAL SCIENCES OF PHILADELPHIA. 355 



O. ferrissi Pils.* Near mouth of Sheridan Canyon, Big Hachet 

 Mountains, New Mexico. 



0. f. morticina Pils. Daniels Peak, Big Hachat Mts., New Mexico. 

 <). hachbtana Pils.* Summit of Big Hachet Mt., New Mexico. 



0. h. cadaver Pils. Daniels Peak, Big Hachet Mts., X. M. 



Notes on the preceding list. 



In presenting a new catalogue of a genus wherein specific values 

 have been so variously estimated, a brief consideration of the growth 

 and changes of opinion on the subject may be in order. In their 

 work of 1869, Binney and Bland recognized Helix strigosa, H. cooperi 

 and H. idahoensis as species, no others being then known. In 1878 

 (Terrestrial Mollusks, Vol. 5) Mr. Binney added H. haydeni and 

 H. hemphilU, and reduced cooperi to a variety of strigosa. In his 

 latest general work, Manual of American Land Shells, 1885, Mr. 

 Binney reduced haydeni to the rank of a variety of strigosa. After 

 this, the remarkable series from Idaho and Utah collected by Henry 

 Hemphill caused Binney to view the entire series of known forms 

 as varieties of stiigosa. This view was generally accepted, as Mr. 

 Binney was conceded to be the leading authority of his time on 

 American land snails. Mr. Hemphill went further than Binney, 

 ranking the whole group as varieties of the Eastern H. alternata Say. 



It may be noted here that a relatively small number of species, 

 from only a part of the area of the genus, were known to Binney 

 and Hemphill. The last 15 species of the list given above were 

 unknown at that time. This includes the whole southern group of 

 species having swollen penes and the Radiocentrum group (with one 

 exception), besides various lately discovered northern forms of very 

 distinct appearance. In dealing with the species and other forms de- 

 scribed prior to 1890 we return to Binney's earlier opinion, and 

 regard strigosa, cooperi, idahoensis, haydeni and hemphilU as species. 

 0. peripherica and 0. hendersoni, while near strigosa, seem to be 

 sufficiently detached to be considered species. 0. rugosa, though 

 near cooperi, is for the time given specific rank. Both of these 

 differ specifically from strigosa by the genitalia. 



Many of the subspecies now recognized were already defined by 

 Binney and Hemphill as varieties of strigosa. If the criterion of 

 intergradation with other forms were rigorously applied to them, 

 several would be judged species; yet in actual practice, and as a 

 temporary expedient until the territory is more fully explored, 

 we take the degree of differentiation into the account. In dealing 

 with the forms of single colonies, scattered over a great extent of 



