340 PROCEEDINGS OF THE ACADEMY OF [May, 



NOTES ON THE ANATOMY OF OREOHELIX, WITH A CATALOGUE OF 



THE SPECIES. 



BY HENRY A. PILSBRY. 



The present study is based chiefly upon material collected by 

 Messrs. Junius Henderson and L. E. Daniels in Utah and southern 

 Idaho. 1 Its object is to determine the characters of the reproductive 

 organs and teeth of the species of this area, both as an aid in the 

 discrimination of the species, and to afford a basis for comparison in 

 further work on the genus. The new catalogue of the species and 

 minor forms of Oreohelix appended, embodies the results of study 

 in the museum and field from time to time during the past ten or 

 fifteen years. 2 



The genus Oreohelix is one of the most difficult groups of land 

 snails within our boundaries by reason of the multiplicity of forms, 

 and the strange parallelism of shell characters sometimes existing 

 between species or races not directly related. This has led to erro- 

 neous identifications, with consequent errors in the data of geographic 

 distribution. 



The shell seems to be especially plastic ; not only are there many 

 local races of various grades of differentiation, but in any colony of 

 some of the species one finds a wide range of variation in the features 

 usually depended on for specific discrimination, such as absolute 

 size, height of the spire, width of the umbilicus relative to the diame- 

 ter, and development of the sculpture. Sometimes colored and 

 white individuals exist in the same colony. If the banded pattern 

 is primitive in the strigosa and cooperi groups, as seems highly proba- 

 ble, then it appears that bandless or white mutations have arisen 

 independently in many colonies, where they sometimes exist with 

 the earlier pattern, apparently in hybrid populations. 



Eighty-six names have been proposed for forms of all grades; 

 many of these are quite insufficiently defined, and no doubt part 



1 For data relating to the localities and shells collected reference must be made 

 to their paper "Hunting Mollusca in Utah and Idaho." A few species collected 

 by Mr. jas. H. Ferriss and the author are also considered. 



2 The writer has personally collected ten of the twenty-four species known. 

 All of the species and subspecies are contained in the collection of the Academy 

 except the following: 0. bruneri Ancey, 0. cooperi stantoni Dall, and 0. strigosa 

 imilaris Dawson. 



