188 CYPKINID^. 



municates with that of the mouth by a comparatively narrow open- 

 ing ; and also the external gill-opening is narrow, the attachment of 

 the gill-membrane to the isthmus taking place immediately before 

 the root of the pectoral fin. Pharyngeal teeth 4 . 1 — 1 . 4, hooked, not 

 denticulated. The short upper and lower caudal rays closely attached 

 to one another. 

 United States. 



1. Exoglossum maxinilingua. 



Cuttlipg, ]\ igger-chub, Day-chub 



Cyprinus maxillingua, LesKeur, Journ. Ac. Nat. Sc. Philad. i. p. 85. 



Exoglossum lesurianum, Rqfinesqiie, I. c. p. 420 ; Cuv. ^ Val. xvii. 



p. 482, pi. 519. 

 maxillingua, Agass. Amer. Journ. Sc. S/- Arts, 1855, xix. p. 215 ; 



Cope, Journ. Ac. Nat. Sc. Philad. xiii. p. 360, pi. 11. fig. 1. 



D. 9. A. 8. L. lat. 55. L. transv. 9/9. 



The height of the body is nearly one-fifth of the total length 

 (■without caudal), the length of the head a little less than one-fourth ; 

 snout scarcely longer than the diameter of the eyt, which is con- 

 tained thrice and two-thirds in the length of the head. Interorbital 

 space flat, of moderate wadth. The origiu of the dorsal fin is scarcely 

 behind that of the ventral, and equidistant between the end of the 

 snout and the root of the caudal fin. Caudal emarginate. There 

 are five longitudinal series of scales between the lateral line and the 

 root of the ventral. A blackish spot at the root of the caudal fin. 



United States. 



a-h. Adult. Kenhawa River. From Mr. Cope's Collection. 



2. Exoglossum mirabile. 



Girard, Proc. Ac. Nat. Sc. Philad. 185G, p. 191 ; U. S. Pac. R. R. 

 JE.rped. Fish. p. 256, pi. 56. figs. 5-8. 



D. 10. A. 9. 



The length of the head is one-sixth of the total (with the caudal). 

 Origin of the dorsal fin in advance of that of the ventrals, and nearer 

 the extremity of the snout than the base of the caudal. A blackish 

 spot on the end of the tail. (Girard.) 



Arkansas Eiver. 



43. RHINICHTHYS*. 



Argyreus, Herkel, in Rnsscfiger''s Rcisen, i. p. i040 (preoccupied). 

 Rliinichthysi, Agassiz, Lake Super, p. 353. 



Argyreus (? and Agosia), Girard, Proc. Ac. Nat. Sc. Philad. 1856, 

 pp. 185, 186. 



Scales very small ; lateral line present. Dorsal fin short, without 



* 1. Argyreus mibilus, Girard, Proc. Ac. Naf. Sc. Philad. 1856, p. 180. — 

 Fort Steilacoom, Puget Sound. 



2. osouhis, (jirardyl.c, and U. W. ^ Mcx. Bouvd. Ichfh. p. 46, pi. 27. 



figs. 9 12. — Kiver Babocomori, a tributarv of the Rio San Pedro. 



3. notabilis, Girard, II. cc. fig.s. 5-8. — Eio Santa Cruz, Sonora. The 



