586 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 49. 



CYPRINODON MACUIARTOS Baird and Girard. 



Examples colleoted in the Sonoyta February 1 are thus described 

 by Doctor Mearns. 



The females of this species are beautifully banded with black on a ground of greenish 

 oUve above and white below. The posterior portion of the opercle is bright steel- 

 blue. The males are not sharply banded and the colors are plainer. They are 

 very tenacious of life, and ascend small streams, entering cold springs whenever 

 possible. 



Gila River at Gila Gty and Adonde Siding; Sonoyta River; 

 spring near Sonoyta River. 



EXPLANATION OF PLATES. 



Plate 76. 



Crania of catostomids. 

 Fig. 1. Notolepidomyzon clarki X 2. Beaver Creek, Arizona, 



2. Pantosteus lahontan X 3. Humboldt River, Nevada. 



3. Catostomus insignis H 1. Colorado River, Arizona. 



4. Xyrauchen cypho X f . Rio Verde, Arizona. 



Plate 77. 



Osseous structure of the dorsal crests of 



Fig. 5. Ictiobus bubalus 



6. Xyrauchen texanus Colorado River, Arizona. 



