FISHES, LAHONTAN SYSTEM OF NEVADA AND NORTHEASTERN CALIFORNIA. 37 



genus have been found in the Oregon Lake region) and, also, in the opposite direction 

 to the Bonneville Basin of Utah, the only localities in which the genus has been found. 

 Pantosieus lahonian closely resembles P. platyrhynchus of the Bonneville. The affin- 

 ities of Richards onius egregius seem to be with R. halteatus of the Columbia or with 

 some similar form of the upper Snake River or the Bonneville. The relationships of 

 Ricfiardsonius microdon are not apparent, unless possibly they may be with R. bicolor 

 of the Klamath or R. caurinus of the Columbia. Cottus heldingi and C. semiscaber 

 have not been compared. The whitefish of the Lahontan and those of the Columbia 

 apparently are alike. 



It seems evident, then, that the fauna of the Lahontan system is related to that 

 of the Oregon Lake, the Columbia, and the Bonneville systems. One, or possibly two, 

 of the trouts may have come from the Sacramento. Of the latter, 5. aquilarum is 

 scarcely to be regarded as a Lahontan species. 



Lahontan sptedes. Probable relationships. 



Catostomus iahoensis Calosiomus of Sacramento, Klamath, or Columbia. 



C. arenarius C. warnerensis, Oregon Lake system. 



Pantosteus lahontan P. platyrhynchus, Bonneville. 



Chasmistes cujus Chasmistes of Klamath or Bonneville. 



Richardsonius egregius. . . .R. balteatus, Columbia. 

 R. microdon. 



SiphaUks obesus S. oregonensis , Oregon Lake system. 



Leucidius pectinifer. 



Agosia robusta Agosia nubila carringtonii, Oregon Lake. 



Coregonus williamsoni. . . .C. williamsoni, Columbia. 



Salmo henshawi S. clarkii, Columbia. 



Salmo aquilarum S. irideus{1), Sacramento. 



S. regalis S. irideusO), Sacramento. 



S. smaragdus. 



Cotlus beldingi C. punctulatus of Columbia or C. semiscaber of the 



Bonneville. 



The Lahontan species are of necessity fluvial and lacustrine, although two genera, 

 Salmo and Coitus, include representatives of forms which may be anadromous or at 

 least able to pass through salt water. With one possible means of dispersal of fluvial 

 fishes eliminated (the open ocean), one may conclude that the Lahontan fishes entered 

 the system directly through channel connections or indirectly by stream capture. It 

 is not presumed that lacustrine and channel forms which never migrate to the headwaters 

 were brought into the system by stream capture, while on the other hand any native 

 species may have entered it through a channel connection with another system. From 

 what is at present known of the habits of the species it may be safely inferred that 

 they reached the system as follows : 



By channel connection: C. cujus, R. microdon, S. obesus, L. pectinifer, S. regalis, S. smaragdus. 

 By stream capture or channel connection: C. takoensis, C. arenarius, P. lahontan, R. egregius, 

 A. robusta, S. henshawi, S. aquilarum., C. williamsoni, C. beldingi. 



Means of dispersal within the system become evident when the geology of the region 

 is consulted. 



