84 FIELD COLUMBIAN' MUSEUM ZOOLOGY. VOL. III. 



bars on sides and a more prominent dark caudal spot than those 

 of the same size from Chihuahua. 



A few of the large males from Mifiaca are black, a \vhite ver 

 tical band on preopercle behind eye: the tins are all black with 

 narrow white margins; a vertical white bar on base of caudal fin. 



The variation in color of the specimens from Mifiaca is much 

 greater than in those from Chihuahua. Specimens from other 

 localities are like those from Chihuahua. One specimen from 

 San Andres. Abundant at the other places. Eggs well devel- 

 oped, evidently near the spawning season. Chihuahua: San 

 Andres: Jimenez: Mifiaca. 



Notropis lutrensis > Baird & Girard ). 



This is the most abundant minnow in northern Mexico. It 

 occurs on both sides of the divide. Many of the specimens from 

 Jimenez. Santa Rosalia and San Andres are highly colored, 

 those from Ahumada are very pale. This species is very variable. 

 The young are more slender than the adults. Scales in series 

 before dorsal 16 to ig. in the lateral line 38. 



Evermann and Goldsborough identify a small specimen from 

 Santa Maria as Xotrofiis frigida. I am inclined to believe that the 

 specimen is the young oithis species. It is too badly mutilated to 

 admit of positive identification. 



The lateral line of this' %pecies 



most of the specimens found in the Conchos basin, though occa- 

 sionally it is absent on a few scales on caudal peduncle. It is 

 less complete in specimens from Santa Maria. The palest spe- 

 cimens are from the two last named regions. The lateral line 

 when not complete usually reaches to the posterior part or the 

 anal tin. \Ve rind no specimens in our collection which seem to 

 be Notropis santamariiz lately described by Evermann and Golds- 

 borough. Eggs well developed: evidently this species spawns 

 early in June. Santa Maria: Ahumada: Chihuahua: Santa Rosa- 

 lia: Jiminez: San Andres: Minaca. 



Notropis formosus I Girard i. 



This species is very abundant at Colonia Juarez. It much 

 resembles .V. lutrensis. but has smaller scales. Scales in the 

 lateral line. 42 to 48. usually 44. Scales before dorsal. i\. Lat- 

 eral line complete except occasionally absent on a few scales. 

 This species does not seem to intergrade with X. lutrensis though 

 no doubt it is a late off-shoot of that species. 



This species spawns early in June. Colonia Juarez. 



