FISTBTES- ^-CYPRINIDAE ARGYREUS DUDCIS. 243 



ARGYREUS, Heck. 



GEN. CHAR. Snout more or less protruding beyond the lower jaw, thus giving the mouth an inferior position. The mouth 

 itself is rather small, surrounded with quite narrow and smooth lips, covered witli a deciduous cartilaginous pellicle in the 

 western species, and provided upon its angle with a small barbel, sometimes very conspicuous. The angle of the mouth not 

 extending as far as the anterior rim of the orbit. The gill openings are separated beneath by a very wide isthmus. The 

 insertion of the ventrals is situated in advance of the anterior margin of the dorsal fin, which is higher than long. The caudal 

 is furcated. The scales are small, longer than deep. The pharyngeal bones are quite narrow, and stouter above than below. 

 The teeth are of the hooked type without grinding surface, strongly hooked and disposed thus : 1 | 4 4 | 2, that is, upon two 

 rows, four in the outer row, and one or two in the inner row. 



SYN. Jlrgyreus, HECK, in Russeg. Reisen, I, H, 1842, 1040. GRD. in Storer, Hist. Fishes of Mass, in Mem. Amer. Acad. 



New S. V, 1855, 287 ; and, in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 185. 

 Rliinichthys, AGASS. Lake Sup. 1850, 353. 



Ileckel includes in this genus two species which are generically distinct, Cyprinus atronasu*, 

 Mitch., and Cypr. rubripinnis. Mus. Par. MS. But Cyprinus rubripinnis is identical with 

 Leuciscus cornutus ; and since Leuciscus cornutus is to enter the genus Plargyrus of Rafi nesque, 

 Cyprinus atronasus remains as the type of the genus Argyreus, which again is identical with 

 Rldniclitliys. It must be recollected, however, that the teeth figured by Heckel under the name 

 of Argyreus rubripinnis are those of Plargyrus cornutus. 



In its external appearance the genus Argyreus resembles Campcstoma, especially in the shape 

 of the head and protrusion of the snout, and also in the situation of the mouth. The natural 

 affinities of these two genera, however, are sufficiently remote to warrant the respective position 

 we have assigned to them in two different groups of the family to which they belong. 



1. ARGYREUS DULCIS, Grd. 

 PLATE LI V, FIGS. 68. 



SPEC. CHAR. Head well developed, constituting the fourth of the length, caudal fin excluded. Mouth large, and barbel 

 conspicuous; lips fleshy. Eye small, sub-circular, its diameter entering six times in the length of the side of the head. Anterior 

 margin of dorsal fin equidistant between the extremity of the snout and the tip of the middle rays of the caudal. Insertion of 

 ventral fins somewhat nearer the angle of the mouth than the base of the caudal. Color greyish yellow above ; yellowish 

 white beneath ; sides sprinkled with an indistinct silvery band. 



SYN. Argyreus dulcis, GRD. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 185. 



The largest specimens observed measured about three inches and a half in total length. The 

 snout is more prominent than in A. atronasus, and less so than in A. nasutus. The head is well 

 developed, constituting the fourth of the length, the caudal fin excluded. The eye is quite 

 small and subcircular, its horizontal diameter entering six times in the length of the side of the 

 head : a little over twice in advance of its anterior rim. The mouth is larger than in most of 

 its congeners, and the barbel much more conspicuous. The dorsal fin, as usual, is higher than 

 long, but its upper margin is slightly convex. Its anterior margin is nearer the extremity of 

 the snout than the insertion of the caudal fin. The latter constitutes a little less than the fifth 

 of the entire length. The anal is somewhat shorter than the dorsal, but its depth is less than 

 the height of the latter. 



D 10 ; A 9 ; C 4, 1, 9, 8, 1, 5 ; V 8 ; P 13. 



The dorsal region is greyish yellow ; the sides yellowish, with an indistinct silvery band ; 

 beneath yellowish white. The dorsal region, including the upper part of the flanks, is spread 

 over with black specks, sometimes observed beneath the silvery band also. 



