GENUS ERIMYZON. 143 



posterior field are also much broader and farther apart than those of the lateral and 

 anterior fields. The scales are smaller upon the anterior portion of the body than 

 upon the sides. Another remarkable peculiarity of this genus consists in the great 

 difference there is among the adults in the form of their fins in the several sexes. The 



young also differ strikingly from the adults both in form and coloration 



The body of Moxostoma is elongated and somewhat compressed, though stouter 

 than that of Ptychostomus and Catostomus proper. The greatest depth is over the 

 veutrals. 



" The head is email ; the small mouth opens obliquely forwards and downwards ; 

 when open the lower jaw is quite prominent. The lips are small and transversely 

 ridged ; the lower one is slightly bilobed. The dorsal is over the ventrals ; its length 

 considerably exceeds its height in the males ; in the females its dimensions are more 

 nearly equal. The pectorals and ventrals are more pointed and longer in the males 

 than in the females. The lower margin of the anal fin is bilobed in the males, while 

 in the females it is simply emarginated ; in both sexes, the anal when bent backwards 

 reaches the caudal. 



" The pharyngeal bones have a greater resemblance to those of the genus Icliihyobus 

 than to any other of the tribe of Catostomi ; the symphysis however is shorter, and 

 the teeth are neither so minute nor so numerous; they increase also more rapidly in 

 size from above downwards, and are more strongly curved inwards, the innermost 

 edge rising into an acute point, which is more prominent in the middle and upper 

 teeth, than in the lower ones." (AGASSIZ, Am. Journ. Sti. Arts, 1855, p. 200.) 



MOXOSTOMA. Girard, 1856. " May be circumscribed by characters more natural than 

 the preceding ones. And the most striking of these, it must be conceded, is the ab- 

 sence of that lateral line possessed by almost all fishes. The body is elongated and 

 compressed ; the head small ; the mouth small also, opening obliquely forwards and 

 downwards. The lips being small and transversally ridged ; the inferior one being 

 slightly bilobed. The anterior margin of the dorsal is situated in advance of the inser- 

 tion of the ventrals. The dorsal fin is either higher than long or else its length is 

 equal to its height, varying somewhat according to the sexes, as well as the anal, 

 which is, however, always deeper than long. The shaft of the pharyngeal bones con- 

 stitutes a very open curve, the convex margin of which is regular and entire. The 

 teeth themselves are very much compressed, strongly curved inwardly, and much 

 larger inferiorly than superiorly." ( GIRARD, Proc.Ac. 2fat. Sc. Pkila. 1856, p. 171.) 



MOXOSTOMA Gunther, 1868. "Scales of moderate size; lateral line none; fins, 

 mouth, gills and pharyngeal teeth, identical with those of Catostomus in all essential 

 points." GUXTHER, Cat. Fishes Brit. Mus. vii, p. 20.) 



ERIMYZON Jordan, 1676. [Name suggested as a substitute for Moxosioma Ag., the 

 type of Moxostoma Raf. (Catostomus anisurus Raf.) not being a member of this genus.] 

 (JORDAN, Bull. Buff. Soc. Nat. Hist. p. 95.) 



ERIMYZON Jordan, 1876." Dorsal moderate ; air-bladder in two parts ; no lateral 

 line; lips usually plicate." (JORDAN, Man. Vert. ed. 1st, p. 292.) 



ANALYSIS OF SPECIES OF ERIMYZON. 



*Body oblong, compressed, becoming gibbous with age, the ante-dorsal region more 

 or less elevated in the adults ; the depth 3^ in length, ranging from 2f in adults 



