52 TKLEOSTKI: EVKNTOGNATIII. — XII. 



XX. [PrfinnxilliirifS not protractile; scales very small; hnrber 



])resent, but iiiiiaitL'J Kiiimcmtiiy.s, 5'J. 



Ik. Maxiliarv with a small liarliel at its extremity (ran-lv olisoletc). 

 «. rreiinixillaries not i)rotractile ; teeth 2, 4—1,2; scales small; 



dorsal bchiiul veiitrals KliiMciiTHys, 69, 



fin. I'remaxillaries protractile. 



t). Teeth 4-4, or 1, 4-4, 1, or 1, 4-4, 0; scales not very small. 



llyuoi-his, 60. 

 00. Teeth, 2, 4-4, 2 or 1. 

 p. Head transversely convex above; teeth without prindinp 



surface Couesius, 61. 



pp. Head flattened above; teeth with grinding surface; 



scales large Platygobio, 62. 



jy. Teeth in the main row 5-5 or 4-5. 



q. Maxillary with a minute barbel placed before its tip; premax- 

 illaries protractile; teeth, 2, 4-5, 2, without grinding surface; 



caudal (in symmetrical Se.motilus, 63. 



qq. Maxillary without barbe4; premaxillaries protractile; anal 

 basis short. 

 r. Teeth two-rowed, 2, 4-5, 2, or 2, 5-5, 2, strongly hooked; 



scales moderate or small I'hoxinl's, 64. 



[As above, the head broad and bluntish; the barbel so minute 

 as to be indistinguishable, in the young of Semotills, 63.] 

 rr. Teeth one-rowed, 5-5, with serrate edges; moutli very small, 

 terminal; I), inserted over V. . . . Oi'Sdi'fEonus, 65. 

 i». Abdomen behind V., compressed to an edge, the scales not crossing 

 it; anal basis elongate (the rays 12 to 18); teeth 5-5, with grind- 

 ing surface and serrate edges; gill rakers rather long; no bar- 

 bels; D. inserted behind V Notemigonl's, 66. 



49. CAMPOSTOMA Agassiz. (^a/iTrij. curve ; oro/ia, mouth.) 



H7. C. anomalum (Rafinesque). Stone Lugger, Stone 

 Roller. IJrownisli, with a brassy histre above, the scales mot- 

 tled ; a black vertical bar behind opercle ; iris orange; D. and 

 A. each with a dusky cross-bar about half-way up, rest of the 

 fm in spring ^ orange; ^ in spring with many rounded tuber- 

 cles on head and body ; young mottled brownish, the fins plain ; 

 scales crowded forward; intestinal canal six to nine times the total 

 length of the body, its numerous convolutions passing above and 

 around the air-bladder, an arrangement found in Catttjiostoma alone 

 among all the vertebrates. D. H; A, 7. Scales 7-53-8. Teeth 4-4. 

 I.,. 4 to 8, W. N. Y, to Texas, and Tcnn. in small streams, every- 

 where abundant ; one of the most curious of American fishes. Very 

 Tariable. 



50. OXYGENEUM Forbes, (d^vr, sharp ; yivos, chin.) 



88. O, pulverulentum Forl)es. F'orm of Afoxostoma : head 

 small, conical; mouth large, terminal ; gill rakers slender; eve 4 

 in head; 31 scales before dorsal; breast scaly. Color pale, the 



