ART. 18. CATOSTOMIDS OF THE BONNEVILLE SYSTEM SNYDER. 5 



The head of P. platyrhynchus is small, the snout bluntly rounded, 

 the lips very broad and pendent, the papillae rather coarse, with 

 about 7 series on the broadest part of the lower lip, and 3 or 4 on 

 the upper. The lower lip is not deeply incised, nor are the incisions 

 at the angle of the mouth especially pronounced. The horny part 

 of the lip is very broad and conspicuous. There are 26 to 28 gill- 

 rakers on the first arch, a distinguishing character when compared 

 with that of P. virescens which has 36 to 40. The caudal peduncle 

 is rather deep, the fin short, with rounded lobes. The anal fin is 

 rounded and extends to the base of the caudal. The pectorals and 

 ventrals are rounded. There are 10 dorsal rays, occasionally 9 or 11. 

 The scales are not so crowded anteriorly as those of P. virescens, 

 and they very gradually grow larger toward the tail. The fontanelle 

 is an open slit of varying width, almost closed in an occasional indi- 

 vidual. The largest specimens measure 180 millimeters. 



The cotypes of Minomus platyrhynchus Cope, from Provo, Utah, 

 are in the United States National Museum (Nos. 15763 and 12906). 

 These have an elongate body, large lips with a horny sheath, open 

 fontanelle, about 80 scales in the lateral line. The cotypes were 

 compared with specimens collected in several localities in the Bonne- 

 ville basin. 



P. platyrhynchus appears to be more abundantly represented in 

 the southern part of the basin than elsewhere, it being the only 

 mountain sucker as yet found in Sevier River and its tributaries. 

 It abounds in Provo River, it was collected in Weber River, but it 

 was not seen in Bear River. It was not seen associated with P. 

 virescens, seeming to prefer the shallow riffles and more turbulent 

 water. It is locally known as the mud sucker, and small examples 

 are confused with fishes belonging to the genus Agosia. Nothing 

 was observed of the habits of the species. An occasional example 

 possessed a narrow, reddish lateral stripe. 



