INTRODUCTION. xxxvii 



Signalosa mexicana (Gunther) : Valles. 



fFundulus heteroclitus (Linnaeus) : Tampico. 



fCyprinodon eximius Girard: Tampico. 



tGambusia affinis (Baird & Girard): Forlon; Valles; Tampico. 



Goodea toweri Meek: Rio Verde. 



*Goodea atripinnis Jordan: San Juan del Rio. 



Platypoecilus variatus Meek: Forlon; Valles; Rascon. 



Poecilia latipunctata Meek: Forlon. 



Poecilia sphenops Cuvier & Valenciennes; Forlon; Valles; Rascon; Tampico. 



fMolienesia latipinna Le Sueur: Tampico. 



Xiphophorus montezumse Jordan & Snyder: Rascon. 



Pomadasys templei Meek: Valles. 



Cichlasoma steindachneri Jordan & Snyder: Rascon; Valles; Forlon. 



Cichlasoma bartoni (Bean) : Rio Verde; Huasteca Potosina. 



Cichlasoma cyanoguttatum (Baird & Girard): Forlon; Rascon. 



Neetroplus carpintis Jordan & Snyder: Forlon; Valles; Tampico. 



Philypnus dormitor (Lacepede) : Tampico; Forlon; Valles; Rascon. 



Chonophorus taiasica (Lichtenstein) : Valles. 



RIO MEZQUITAL SYSTEM. 



The Rio Mezquital rises east of the central range of the Sierra 

 Madre Mountains and empties into the Pacific Ocean a short distance 

 north of the mouth of the Rio Grande de Santiago. I visited this 

 river at Durango where it is a rather small stream with a sluggish 

 current. The collection of fishes made here is of especial interest 

 because all of them, except three,* belong to the fauna of the 

 Rio Grande. Characodon jurcidens J. & G., is known from this river 

 only near its mouth. Of the eleven species from this river Chara- 

 codon garmani J. & E., Characodon furcidens J. & G., and Chirostoma 

 mezquital Meek, are the only ones that can properly be ascribed to 

 the southern or tropical fauna. 



The fishes of the upper portion of the river certainly indicate that 

 it was at some former time a portion of the Rio Grande system. 



Characodon garmani Jordan & Evermann is very abundant in a 

 large spring in the city of Durango. 



Near Labor, about eight miles from Durango, is a large spring 

 from which was taken three species of fishes. The following is a list 

 of fishes known from this river system 



Amiurus price! (Rutter) : Durango. 



Pantosteus plebeius (Baird & Girard) : Durango. 



*Myzostoma austrinum Bean: Durango. 



Hybognathus episcopus (Girard): Durango; Labor. 



Leuciscus nigrescens (Girard) : Durango. 



Nototropis ornatus (Girard) : Durango. 



Characodon garmani Jordan & Evermann: Durango; Labor. 



*Characodon furcidens Jordan & Gilbert: Tuxpan. 



Cyprinodon latifasciatus Garman: Labor; Durango. 



*Chirostoma mezquital Meek: Durango. 



Etheostoma pottsii (Girard) : Durango. 



