INTRODUCTION. xxxiii 



RIO SANTA MARIA. 



This stream is parallel to the Rio Casas Grandes and flows into 

 Lago de Santa Maria about 10 miles southeast of Lago de Guzman. 

 These lakes are separated by a comparatively low ridge, but so high 

 that their waters have not been connected for a considerable time. 

 The fishes of this stream are but little known. The following is a list 

 of those known from it at present : 

 Pimelocephales confertus (Girard) : Santa Maria. 

 Leuciscus nigrescens (Girard) : Santa Maria. 

 Nototropis lutrensis (Baird & Girard) : Santa Maria. 

 Nototropis santamariae Evermann & Goldsborough : Santa Maria. 

 Nototropis frigidus (Girard) : Santa Maria. 

 Cyprinodon elegans Baird & Girard: Santa Maria. 



RIO CARMAN. 



This is a small river east of the Rio Santa Maria and flows into 

 Lago de Patos. This lake becomes dry by the end of the dry season, 

 and there is no water in the river for some distance above Ahumada. 

 The few fishes known from this river basin were taken from an irrigat- 

 ing ditch near Ahumada, and from a spring at San Jose. 

 Pantosteus plebeius (Baird & Girard:) Ahumada. 

 Leuciscus nigrescens (Girard) : Reported above Ahumada. 

 Nototropis lutrensis (Baird & Girard) : Ahumada; San Jose. 

 Cyprinodon eximius Girard: Ahumada. 



RIO SAUZ. 



This is a small stream about fifteen miles in length, situated a 

 short distance north of the City of Chihuahua. At Sauz, about the 

 middle of its course, it contains a small amount of running water 

 during the dry season. 



The following four species of fishes are known to occur there : 

 Pantosteus plebeius (Baird & Girard) : Sauz. 

 Nototropis lutrensis (Baird & Girard) : Sauz. 

 Cyprinodon eximius Girard: Sauz. 

 Gambusia affinis (Baird & Girard) : Sauz. 



LAGO DE CASTILLOS. 



This small mountain lake is situated on the divide between the 

 head waters of a tributary of the Rio Grande and of the Rio Yaqui. 

 It becomes nearly dry by the last of June. There are a number of 

 springs in this region which are said to contain small fishes. The fol- 

 lowing is the only species I obtained in a pond left by the drying up 

 of this lake: 

 Leuciscus nigrescens (Girard) : Bustillos. 



RIO NAZAS. 



This is a river of considerable size in central Mexico. It rises in 

 the Sierra Madre Mountains and flows into Lago de Mayran. By the 



