INTRODUCTION. xxxix 



RIO SONORA SYSTEM. 



Concerning the fishes of this river very little is known. The two 

 or three species known from it indicate that its fauna is that of the 

 Rio Colorado. 



Ptychocheilus lucius Girard: Northern Sonora. (River basin doubtful.) 



Agosia chrysogaster Girard: Hermosillo. 



Pcecilia occidentalis (Baird & Girard) : Hermosillo. 



COLORADO RIVER SYSTEM. 



This river drains but a very small portion of Mexico. I have here 

 included only those fishes found between Yuma and the Gulf of 

 California. I am uncertain as to whether the two species of Agosia 

 should be credited to the Rio Colorado or to the Rio Yaqui. The 

 Rio Santa Cruz may possibly belong to the Rio Sonora. 

 Xyrauchen cypho (Lockington) : Yuma; Horseshoe Bend. 

 Ptychocheilus lucius Girard: "Northern Sonora"; Yuma; Horseshoe Bend. 

 Gila elegans Baird & Girard: Yuma; Horseshoe Bend. 

 Agosia oscula (Girard) : Rio Santa Cruz ; Sonora. 

 Agosia chrysogaster Girard: "Rio Santa Cruz." 

 Plagopterus argentissimus Cope: Yuma. 

 Cyprinodon macularis Baird & Girard: Lerdo. 

 Gillichthys detrusus Gilbert & Scofield: Horseshoe Bend. 



LOWER CALIFORNIA. 



There are only a few streams in Lower California, and but little 

 is known concerning the fishes which inhabit them. Mr. Heller 

 found but one species, Salmo irideus Gibbons, in the streams of the 

 northern part of this peninsula. Three species have been taken from 

 either La Paz or Cape San Lucas, most likely from the former place. 

 The other species known from the, fresh waters of this region were 

 taken in the Rio San Jose, near San Jose del Cabo. 



Salmo irideus Gibbons: San Antonio. 



Fundulus vinctus Jordan & Gilbert: La Paz; or Cape San Lucas. 

 Fundulus extensis Jordan & Gilbert: La Paz or Cape San Lucas. 

 Characodon furcidens Jordan & Gilbert: La Paz or Cape San Lucas. 

 Siphostoma starksi Jordan & Culver: San Jose del Cabo. 

 Agonostomus monticola (Bancroft) : San Jose del Cabo. 

 Neomugil digueti Vailliant: Sierra de las Cacachilas de Santa Cruz. 

 Pomadasys bayanus Jordan & Evermann: San Jose del Cabo. 

 Philypnus dormitor (Lacpede) : San Jose del Cabo; Cape San Lucas. 

 Dormitator maculatus (Bloch) : San Jose del Cabo. 

 Eleotris pictus Kner & Steindachner: San Jose del Cabo. 

 Chonophorus taiasica (Lichtenstein) : San Jose del Cabo. 



RIO GRANDE DE SANTIAGO SYSTEM. 



The Rio Grande de Santiago and its largest tributary form the 

 longest stream in Mexico, draining a considerably elevated plateau 



