FRESHWATER FISH FAUNA 



209 



Bonneville and upper Snake (Columbia) drainages. The middle 

 section, in the vicinity of and including the Little Colorado River and 

 the ancient White River, holds in common the species of the endemic 

 cyprinid genus Lepidonieda (Miller and Hubbs, in press). The Gila 

 River division has 8 endemic species, most of which are likely au- 

 tochthonous but at least 2 {Cyprinodon and Poeciliopsis) of which 

 were derived from the east and south, respectively. Except for 

 headw^ater types, which are identical with or representative of 

 headwater species of adjacent basins, 71 per cent of its total of 35 

 species are confined to the Colorado. This bespeaks a long isolation 

 from surrounding faunas. Only limited faunal exchange has taken 

 place with the Rio Yaqui (1 sucker and 2 minnows have moved 

 south from the Colorado and Poeciliopsis has moved northward 

 from the Yaqui). 



Sacramento Complex 



The Sacramento-San Joaquin, streams entering Monterey Bay 

 and San Francisco Bay, and the Russian River and other coastal 

 streams north to the Mad River are included in this complex. Nine 

 of the 13 families occurring here contain semi-marine species, and 

 one {Hysterocarpus traski of the Embiotocidae, Fig. 18) is the only 

 freshwater representative of an otherwise wide-ranging marine 

 family. The only native centrarchid west of the Rocky Mountains 

 survives in the lowland waters but has been greatly reduced from its 



'''--^^. 







Fig. 18. Tule perch, Hysterocarpus traski, the only freshwater mem- 

 ber of its marine family (Embiotocidae). (From original drawing by W. S. 

 Atkinson; see Jordan and Evermann, 1900, Fig. 577.) 



