24 Evermann — A New Trout from Lower California. 



ceivable that, when the deserts of Panamint and Amargosa were 

 great lakes or inland seas, trout may have been able to reach 

 Pacific drainage in the northern part of Lower California. From 

 what is known of the geological and hydrographic history of 

 the region this, however, is a remote possibility. 



These same difficulties arc encountered in considering the 

 possible origin of the Lower California trout from the southern 

 High Sierra. The same deserts were to cross and the distance 

 is greater, unless they came down via Tehachapi Pass and the 

 San Bernardino and San Jacinto ranges, which would have 

 brought them over to the coastal streams. 



These coastal streams, however, were probably stocked from 

 other Coast Range streams farther north. This extension was 

 aceomplished, in all probability through short journeys in the sea 

 from the mouth of one stream to that of the next. In this way 

 trout succeeded in extending their range as far down the coast 

 as the mouth of the San Luis Key, if that be a natural trout 

 stream, as has been reported. From that stream, in excep- 

 tionally favorable seasons they could have extended their range 

 southward to the mouth of the Rio San Ramon, a distance of 

 approximately 100 miles. This may have been accomplished 

 in a single advance or intervening streams may have been 

 utilized and the advance made in two or more stages. The in- 

 tervening streams such as the San Diego and the Sweetwater 

 are not known to contain trout and some of them do not ordi- 

 narily reach the sea. It is not improbable that they formerly 

 were better suited to trout and that trout may have inhabited 

 them at one time. 



Still more conclusive evidence that the San Ramon River was 

 stocked from the sea, or at least that the trout ascended the 

 river is found in the fact that there are no trout in its head- 

 waters. The San Ramon has its sources among tin' highest 

 parts of the Sierra San Pedro Martir. About 12 miles above 

 Rancho San Antonio is a considerable fall which trout can not 

 possibly ascend, and above these falls it is said that trout are 

 not found. 



These geographic fads, together with the fact that the Lower 

 California trout is a rainbow trout rather than a cutthroat, lead 

 to the conclusion that the Rio San Ramon in all probability 

 was originally stocked with trout from the coastal streams to 



