May, 1902. The Ich rnvoi.oov oi- Mf.xko — ]\Ii:kk. 123 



* been equalh' explored, though it is likel)' that all have about tht; 

 same fauna. From these basins have been taken the following 

 species: 



Pantosteus plebius. Casas Grandes. 



Campostonta ornatum. Casas Grandes. 



Pimephales confer/us. Casas Grandes; Santa Maria. 



Leuciscus nii^rescens. Casas Grandes; Santa' Maria; Carmen; 

 Castillos. 



^Notropis santamarice. Santa Maria?. 



Notropis fonnosus. Casas Grandes. 



Notropis lutrcnsis. Casas Grandes; Santa Mariaj; Carmen. 



Cyprinodon elegans. Casas Grandes; Santa Maria;; Carmen. 



Of these 8 species none have been recorded from the Gila 

 River or the Rio Sonora. All, except Xotj'opis santaniariir and 

 Notropis for inosus, are reported from the head waters of the Rio 

 Yaqui in Chihuahua, and from the Rio Conchos. The two 

 exceptions are species closel}' related to Notropis lutrensis, an 

 extremely variable and widely distributed minnow, and which is 

 abundant in the Carmen and Santa Maria rivers. N'otropis ornatus 

 is common to both the Rio Conchos and Rio Yacjui, but at pres- 

 ent is not known from any of the 4 small river basins. No 

 other species than those here mentioned is known to be com- 

 mon to these two river systems. 



Ameinrus pricei is a bull-head found in the upper Yaqui 

 Basin. A large catfish is reported to be found further down the 

 river, which may be the adult of this species. 



A large catfish is also reported by the natives to be in the Rio 

 Conchos. It is likely that it is Ameinrus pricei or a closely 

 related species. To find Ameinrus in the Rio Yatjui was unex- 

 pected and a little surprising at the time. The genus Ameiurus 

 comprises a large number of species found throughout the East- 

 ern United States, but none are yet definitely recorded from 

 Eastern Mexico, though no doubt one or more species exist 

 there. 



Leuciscus nigrescens, Leuciscus purpureus, Leuciscus niger and 

 Leuciscus intermedius are four variable and closely related species. 

 It is barely possible that all may prove to be the same. This 

 fact cannot well be ascertained except by a careful study of a 

 large series of specimens from the different river systems where 

 found. 



*Xotropis frigidus. A small specimen in bad condition from Santa Maria was identified by 

 Evermann & CioTdsborough as belonging to this species; owing to their luu-ortaii) idL-ntification of it 

 I omit it here. 



