NO. 2125. FISHES FROM THE GULF OF CALIFORNIA— SNYDER. 575 



The color of the ventral surface varies from pure white to a beautiful yellow. The 

 upper surface is dark, the line of division between dark and light being sharply 

 defined and located 3 to 5 scales below the lateral line. 



This is a large scaled sucker with elongate head, large lips, and 

 deep caudal peduncle. It has been reported from the lower parts of 

 the Colorado system, its range evidently not extending up into the 

 swift-flowing streams of the mountains. 



Doctor Mearns secured specimens from the Verde and Santa Cruz 

 Rivers and from Beaver Creek near Fort Verde. 



CATOSTOMUS SONORENSIS Meek. 



Some small suckers from San Bernardino Creek are identified as 

 C. sonorensis. These are somewhat more slender than that described 

 by Meek,^ and the scales and fin rays are similar to those of C. in- 

 signis. No examples of the latter of similar size are available for 

 comparison.^ 



San Bernardino Creek near the international boundary. 



NOTOLEPmOMYZON CLARKI (Balrd and Girard). 



A comparative study of the species usually assembled in the genus 

 Pantosteus discloses the fact that they are separable into two well- 

 defined, natural groups, one characterized by a thick cranium in 

 which the parietals and frontals meet in a close, strong suture (fig. 1), 

 and another by a relatively thin cranium where the parietals and 

 frontals are separated by a long, often very narrow, fontanelle which 

 apparently does not close even in very old individuals. For the first 

 group the name Notolepidomyzon ^ is available, while Pantosteus 

 must be retained for the second. 



Catostomus has a broad, usually rectangular fontanelle (fig. 3), 

 and the lips are not armed with a horny sheath as in Notolepido- 

 myzon and Pantosteus. 



Recent authors recognize three species of Pantosteus in the Colorado 

 system, namely, P. clarM (Baird and Girard), P. arizonae Gilbert, 

 and P. delpMnus (Cope).'* 



Specimens measuring about 240 mm. from Beaver Creek near Fort 

 Verde, are referable to P. clarki, as they possess the very large and 

 somewhat rounded scales of the anterior upper parts which character- 

 ize that species. The scales in the first row above the lateral fine are 



1 Field Columb. Mus. Publ. 93, Zool. Ser., vol. 5, p. 32, pi. 6. 



* The type oi Catostomus bemardini No. 174, U.S.N.M., a specimen measuring 193 mm., has 12 rays in the 

 dorsal, 7 in anal, 74 scales in lateral series, 15 in series between lateral line and middle of back, 12 below lateral 

 line, and 33 between occiput and dorsal fin. 



8 Fowler, Henry W., Proc. Acad. Nat. Sci., Phila., 1913, p. 47, Notolepidomyzon type arizonae. Cope and 

 Yarrow; Wheeler's Explor. west of the 100th merid., vol. 5, 1875 (1876), p. 673, Pantosteus type platyrhyn- 

 chus. It will be noted that Notolepidomyzon was characterized by the size of the scales, wliile the type 

 of Pantosteus has a large fontanelle. 



* Proc. Acad. Nat. Sci. Phila., 1854, p. 27, Catostomus clarki; U. S. and Mex. Bound. Surv. Ichthyol., 

 p. 38, pi. 22, Minomus clarki; Bull. 47, U. S. Nat. Mus., p. 170, Pantosteus arizonae; Proc. U. S. Nat. Mus., 

 vol. 20, p. 488, pi. 36; U. S. Geol. Surv. Wyoming, Foiuth Ami. Rept., 1870 (1871), p. 435, Minomus 

 delpMnus. 



