214 K. R. MILLER 



Lahontan. Evidently the invasions were not simultaneous since the 

 movement southward of Siphateles was timed so that this genus did 

 not become established in the Colorado complex. The hypothesis 

 that Siphateles (as well as Catostomus and Rhinichthys) entered the 

 Owens River portion of the Death Valley system from the Lahontan 

 basin via the Mono Lake basin (Hubbs and A/Iiller, 1948, p. 79) fails 

 to explain why Prosopium, Salmo, and Cottus, common associates of 

 Catostomus and Rhinichthys (if not of Siphateles), are absent from 

 the Death Valley system. The common occurrence of Siphateles 

 points to an earlier, low-elevation connection such as may have per- 

 mitted the entrance into the Lahontan basin of Fundulus and 

 Gasterosteus. 



OTHER DRAINAGES 



The fauna of the Rio Yaqui, of coastal streams from Baja Cali- 

 fornia to central California, and of certain isolated waters not in- 

 cluded in the seven centers of endemism are briefly discussed here. 



Yaqui River 



The fauna of the Yaqui River of northwestern Mexico is distin- 

 guished from that of the drainages already discussed by the presence 

 of a native freshwater catfish {Ictaluriis pricei), a cichlid (Cichla- 

 soma beani), and a host of tropical fishes of marine derivation 

 {Dorosoma, Lile, Galeichthys, Centropomus, Dormitator, Trinectes, 

 etc.). It has the largest number of families, 16, and is second to the 

 Columbia and Sacramento in number of genera. Only 12 of its 31 

 species are primary freshwater fishes (Table I). Not included in 

 the tabulation are Gila ditaenia (Miller, 1945a), of the Rio de la 

 Concepcion, and Catostomus wigginsi (Herre and Brock, in Herre, 

 1936), of the Rio Sonora, both independent tributaries of the Gulf 

 of California lying between the Yaqui and Colorado drainages. The 

 relationships of the minnow are with Gila purpurea of the Yaqui 

 and G. orcutti of southern California; those of the sucker have not 

 been determined. 



Seven of the 12 primary species are Rio Grande types, which, it is 

 plausibly postulated, have entered the Yaqui by stream capture 

 across the Sierra Madre Occidental (Meek, 1904, p. xxvii). These are 

 Pantosteus plebeius, Campostoma ornatum, Gila'' nigrescens,'' Notropis 

 mearnsi, N. ornatus, Pimephales promelas, and Ictalurus pricei. Pre- 



