556 FISHES PROM THE GILA RIVER, ARIZONA. 



Ventrals small, anterior insertion opposite middle of dorsal, their long J 

 ray (3d) but slightly shorter than that of dorsal. Pectorals narrow bd 

 long, reaching to front of pubic bones, their longest ray (4th) long] 

 than that of dorsal and equal to that of ventral. Scales large long] 

 than deep, smaller anteriorly and crowded, largest on peduncle of tail 

 and smallest on breast. 



Color (alcoholic): above, and sides to axils of pectorals, dark brown 

 the scales being dark at base and covered with dark punctulationa 

 below yellow; the fin membranes dark. Lateral line abruptly decurveo 

 near its origin, then running on median line of body to caudal tin 

 Head4£inbody; depth U: D.lltol2; A. 7; scales 11-58 to 60-lS 

 One of the typical examples has been sent to the TJ. S. National 

 Museum. 



3. Catostomus insignis Baird & Girard. 



One specimen, 12i inches long. Scales on sides of moderate size, 

 larger anteriorly than posteriorly, but so covered that the contrary 

 seems to be true ; the anterior scales are of a circular outline, the poste- 

 nor nearly twice as long as deep. Those on the back very large, those 

 on the belly very small, only about half as large as the former. 



4. Catostomus Clarki Baird & Girard. 



One specimen, 12 inches long. The scales on back not quite so large 

 as those of C. insignis, but otherwise similar in size and arrangement to 

 those of that species. Scales on lateral line 68. 



5. Xyrauchen* cypho (Lockington).— Buffalo Fish. 



This species, Catostomus cypho Lockington, seems to be the type of a 

 distinct genus, Xyrauchen Eigenmaun & Kirsch, gen. nov 



The genus Xyrauchen agrees with the genus Catostomus, except in 

 having behind the occiput a very large sharp edged hump formed by 

 the singularly developed anterior interneurals. 



The anterior portion of the hump is supported by a large interneural 

 formed by a thick central pillar with anterior and posterior wings, the 

 former coming to a point on the medial projecting plate of the supra- 

 occipital, forming a large opening beneath it; the latter wing is some- 

 what smaller and articulates with the second interneural. The upper 

 margin of the first interneural is highest at the point of the central pil- 

 lar from which it slopes anteriorly and posteriorly. « The base of the 

 central pillar is expanded transversely, giving a double articulating 

 surface on its under side " (Lockington). The next interneural is a thin, 

 flat, sub-rectangular plate; the third is an irregular flat plate about half 

 as arge as the second, while the next three are small flat plates above 

 and bent forward. 



The interneurals of the dorsal fin with a central ray and an anterior 

 and posterior expansion, which d oesnot, however, extend to their lower 



* Zvpbg, razor ; avxvv, nape. 



