FRESHWATER FISH FAUNA 211 



that Rhmichthys osculus (Agosia nuhila and A. klamathensis of 

 Snyder) moved in the same direction, since the species does not 

 otherwise occur south of the Coquille River, Oregon, or north of 

 the Sacramento River system. Ten genera and 19 species have been 

 stopped by the Falls; only one of these, Catostomus rimiculus, is a 

 primary fish (known elsewhere only from Rogue River, Oregon). 

 Two species of Cottus (C. prmceps, Fig. 19, and C. tenuis) are con- 

 fined to the Upper Klamath basin. The percentage of endemism at 

 the species level is lowest in this system. 



Columbia Complex 



This system, as here expanded to include not only the Columbia 

 River but also the Umpqua, Malheur, Fraser, Skeena, and Stikine 

 rivers, is the largest of the centers of endemism (Fig. 1). The Snake 

 River above American Falls is not included in the complex, as this 

 part is faunally allied to the Bonneville Basin and received the outlet 

 of Lake Bonneville. In correlation with its size, the Columbia has 

 the richest fauna — 15 families, 29 genera, and 57 species. However, 

 its primary fishes, though including four families, are not as numer- 

 ous as in the smaller Colorado complex (Table I). The accessibility 

 of the Columbia to the wealth of marine and semi-marine types ac- 

 counts for its large total fauna but also is correlated with a relatively 

 weak primary fauna with specific endemism at about the same level 

 as that of the Klamath River. A noteworthy element of the fauna is 

 the richness of the genus Cottus, the Columbia River system alone 

 containing about 12 species (6 endemic). Salmonoids also are nu- 

 merous, constituting 6 genera and 13 species, including Thymalliis 

 arcticus from the Stikine River only and Coregonas clupeaformis 

 from the Skeena and Fraser rivers (Lindsey, 1956, p. 763). 



The primary fauna shows relationships with that of eastern United 

 States: 4 species occur on both slopes of the Continental Divide 

 {Catostomus catostomus, Hyhopsis plumbea, Hybognathus hankinsoni, 

 and Rhmichthys cataractae). Two, Siphateles bicolor and Pantosteus 

 platyrhynchus, are invaders from the Great Basin. Novumbra huhbsi 

 and Columbia transmontana are ancient (Miocene?) relicts. 



Bonneville System 



This is the largest of the Great Basin drainages with about 21 

 species, 67 per cent of which are endemic (Table II). Included is the 



