Introduction. xxxi 



life; but after a few months of exposure to the piercing rays of the 

 tropical sun the character of the country changes, assuming the ap- 

 pearance of a parched desert. The rivers, which are large in the 

 rainy season, become very small by the end of the long dry season. 

 Many of the lakes in this region become dry and the streams which 

 flow into them contain little water except in the upper part of their 

 courses where they are fed by mountain springs, and streams of this 

 character contain but few species of fishes. 



RIO GRANDE AND ITS PRESENT TRIBUTARIES IN MEXICO. 



Below is a list of fishes known from this drainage area: 



Lepidosteus osseus (Linnaeus): Santa Rosalia; San Juan. 



Ichthyaelurus furcatus (Le Sueur) : Brownsville. 



Ichthyaelurus punctatus (Rafinesque) : El Paso. 



Amiurus lupus Baird & Girard: San Juan; Montemorelos. 



Amiurus natalis (Le Stieur) : Brownsville. 



Leptops olivaris (Rafinesque) : El Paso; Santa Rosalia. 



Carpiodes tumidus (Girard): Ft. Brown; Brownsville. 



Carpiodes microstomus Meek: Santa Rosalia; Jimenez. 



Carpiodes elongatus Meek: San Juan; Montemorelos. 



Pantosteus plebeius (Baird & Girard) : San Andres. 



Catostomus conchos Meek: Jimenez. 



Myzostoma congestum (Baird & Girard): Monterey; Santa Rosalia; San Juan; 

 Montemorelos; El Paso. 



Campostoma ornatum Girard: Chihuahua; San Andres; Santa Rosalia; Jimenez. 



Campostoma anomalum (Rafinesque): Cadereita; Acapulco; San Juan; Monte- 

 morelos. 



Campostoma formosulum Girard: Brownsville. 



Hybognathus episcopus (Girard): Chihuahua: Jimenez; Comanche Spring; Sal- 

 tillo; Monterey; Cadereita; Montemorelos; Ft. Brown; Brownsville; Buena 

 Vista; Guajuco. 



Pimelocephales confertus (Girard): San Andres; Chihuahua; Santa Rosalia; 

 Jimenez; Brownsville. 



Leuciscus nigrescens (Girard): Chihuahua; San Andres; Saltillo. 



Abramis chrysoleucus (Mitchill) : Brownsville. 



Cochlognathus ornatus Baird & Girard; Brownsville. 



Nototropis braytoni (Jordan & Evermann) ; Cadereita; San Juan; Montemorelos. 



Nototropis robustus Meek: Santa Rosalia; Jimenez. 



Nototropis chihuahua Woolman; Chihuahua; San Andres; Santa Rosalia; Jim- 

 enez. 



Nototropis ornatus Girard: Chihuahua; Jimenez; San Andres. 



Nototropis orca Woolman; El Paso. 



Nototropis lutrensis (Baird & Girard): China; Cadereita; Monterey; Acupulco; 

 Chihuahua; Santa Rosalia; San Andres; Jimenez; Brownsville.- 



Nototropis macrostomus (Girard): China; San Juan; Montemorelos. 



Nototropis santarosaliae Meek: Santa Rosalia. 



Phenacobius scopifer (Cope) : Brownsville. 



Rhinichthys simus Garman: "Coahuila"; Santa Rosalia; Montemorelos. 



Hybopsis aestivalis (Girard): Cadereita; El Paso; San Juan. 



Cousius adustus Woolman: Chihuahua. 



