100 BULLETIN 114, UNITED STATES NATIONAL MUSEUM. 



of its range and variable toward hoylii in tlie northern. If we sug- 

 gest that it was evolved from loylii by adaptation to a different 

 habitat, we consider a possibility that may have no proved counter- 

 part elsewhere, and that in this case has, as yet, no support from 

 observation in the field. 



The mutation theory, even though it rests upon no direct evidence 

 in this case seems at present to offer the best exp anation of the 

 origin of this form. On the basis of this theory the origin may then 

 be hypothecated as follows: Calif orniae originated from hoylii by 

 mutation, somewhere in the Great Valley of California. It spread 

 southward west of the Sierra Nevada Mountains and the deserts of 

 southwestern California becoming more different from boylii toward 

 southwestern California. From here it extended its range into 

 Lower California to Cape San Lucas At some point in this penin- 

 sula, probably pretty well south, it became modified into the color 

 variety nitida. 



It will be recognized that more information is essential to an ade- 

 quate explanation of calif orniae. 



