10 



BULLETIN 17 5, UNITED STATES NATIONAL MUSEUM 



What detailed observations have been recorded are included in the 

 discussions of the several forms. 



It is evident from the wide range of the genus that it must be little 

 restricted as to habitat. Although the various forms are each more 

 restricted than the genus as a whole — sayi, for example, bemg typi- 



FiGUEE 5.— Head of PUuophis deppei jani: a, From the side; 

 b, from above. 



Figure 6.— Dissected hemipenis 

 of PUuophis sayi sayi 



cally a plains form, while deserticola is more or less restricted to desert 

 regions— many of the forms show a wide range of habitat. Thus, in 

 several cases the same subspecies is found with equal frequency in 

 desert lowlands and on mountainsides at an altitude of several thou- 

 sand feet. The eastern forms are generally believed to be confined to 

 the pine forests and sandy barrens of the Coastal Plain, but m. melano- 

 leucus appears to be equally common in the Allegheny Mountain 

 region. 



