FAMILY IV. CATOSTOMID^E. 33 



28. Catostomus conchos Meek. 



Catostomus conchos Meek, Field Col. Mus. Pub. 65, 1902, 75 ; Jimenez. 



Basin of the Rio Conchos, in Chihuahua. 



Head 4^; depth 4%; D. 9; A. 7; scales 13-80-13. Body robust, 

 terete, not much compressed, except posterior third; profile convex; 

 head broad; interorbital area convex, its width 2% in head; lips thick, 

 papillose, the papillae on the upper lip in about 9 rows; lower lip broad, 

 4^ in head from anterior to posterior margin ; lower lip deeply incised, 

 its lobes meeting at a very obtuse angle; dorsal fin as high as long, 

 its base i.K in head; origin of dorsal fin nearer tip of snout than base 

 of caudal by a distance equaling ^3 head ; margin of dorsal fin slightly 

 convex ; base of ventrals under seventh dorsal ray ; pectoral fin i X in 

 head; distance from tip of pectoral to base of ventral 2 in pectoral fin; 

 ventral fins if in head, their tips not reaching anal; lateral line slight- 

 ly decurved anteriorly; no fontanelle; caudal fin not deeply emarginate 

 the lobes about equal. 



Color light steel blue on back, shading into dark olive; sides 

 lighter below, especially on posterior half of body where the line be- 

 tween the light and dark color is very marked ; on anterior half of the 

 body the colors gradually merge into one another; young with the 

 black lateral blotches. Length 1 2 inches or more. 



At present this species is known only from the type locality. 



12. Xyraucheii Eigenmann & Kirsch. 

 RAZOR-BACK SUCKERS. 



'Xyrauchen Eigenmann & Kirsch, Proc. U. S. Nat. Mus., 1888, 

 556. (Type, Catostomus cypho Lockington.) 



Body rather elongate, compressed; nuchal region with a large 

 sharp-edged hump, formed by a singular development of the inter- 

 neural bones, otherwise as in Catostomus. 



29. Xyrauchen cypho (Lockington). RAZOR-BACK SUCKER. 



' Catostomus cypho Lockington, Proc. Acad. Nat. Sci. Phila., 1880, 

 237 ; Colorado River at mouth of the Gila, Arizona: Gilbert & 

 Scofield, Proc. U. S. Nat. Mus., 1898, 491; Colorado River at 

 Yuma, and Horseshoe Bend. 

 Basin of the Colorado River. 



Head 4; depth 4; D. 13 or 14; A. 7; scales 14-72 to 77-13. Body 

 stout, compressed; the head small, low, the profile ascending to the 

 prominent nuchal hump, which is largest in adults; anterior edge of 

 hump straight, sharp, and without scales; mouth wide, inferior; upper 

 lip with two rows of papillae; lower lip deeply divided, with 8 rows; 



