164 CONTRIBUTIONS TO NOETH AMERICAN ICHTHYOLOGY IV. 



The species may be divided as follows :* 



^ Scales not especially deeper tLau long; not closely imbricated. 



* Teeth 4-4 ; species of small size. 



t Teeth with grinding surface more or less developed. (Hybopsis Cope, non Ag. ) 



(a.) Scales in the lateral line more than 45 alta. sallwi. 



a. Scales in the lateral line 43 or 44 tmUtana, taurocepliala, hannatura. 



aa. Scales in the lateral line 32-37. 



sjyectrunciila, nubila, fretensis, longtrosfris, straminea. 

 volucella, microstoma, lineolata, missuricnuis, procne. 

 tt Teeth without grinding surface. (Cliola.) 



1). A black spot on anterior edge of dorsal and one at the base of the caudal. 



vigilax. 



l)h. No black spot on anterior edge of dorsal cliJora, niyrotceniata. 



*** Teeth two-rowed. 



X Teeth without grinding surface cohifis, sima. 



tt Teeth with grinding surface more or less developed. (Hudsonius Grd.) 



saludana, storcriana, hudsonia, euryopa. 

 §5 Scales deeper than long, very closely imbricated aloug sides of the body. 



* Teeth 4-4. 



t Edges of teeth entire. (Codoma Girard.) 



t Teeth wi th grinding surface developed iris, jmjalis. 



tt Teeth without grinding surface. 

 a. Dorsal fin inserted notably behind ventrals; bead very short and blunt, al- 

 most round ; vitiata, ornata. 



aa. Dorsal fin inserted directly over ventrals; head moderate, subconic. 



callisema, 



the premasillary on the level of the puiiil, the maxillary not reaching the front of the 

 pux^il. Jaws equal. Preorbital large. Scales not closely imbricated, 19 in front of 

 dorsal fin. Dorsal over ventrals. Caudal peduncle deep. Bluish, sides silvery, 

 fins plain. Head 4J ; depth 3|. D. 8 ; A. 8 ; scales 8-4G-4 ; teeth 4-4, with narrow 

 grinding surface. Lake Tui)ataro, Guanajuato. 



(Hudsonitts alius Jordan, Proc. U. S. Nat. Mus. 1879, 301.) 



(&.) C. sallwi (Giinther) J. & G. Caudal peduncle not quite twice as long as deep. 

 No barbels. Snout obtusely conical, longer than the eye, which is one-fifth the length 

 of head. Upper jaw slightly overlapping the lower. Maxillary not extending to eye. 

 Dorsal immediately behind ventrals. Fins short. Browuisb green above, minutely 

 dotted with black along the sides. Head 4; depth 3|-. D. 7; A. 6; Lat. L 54; teeth 

 4-4, long, curved, with grinding surface. Intestinal canal with few convolutions. 

 L. 3^ inches. Cuernavaca, Mexico. {Giinther.) 



(Ceraticlithys sallcei Giinther, vii, 484: Hndsonius sallwi Jordan, Proc. U. S. Nat. Mus. 

 1S79, 226.) 



(c.) C.nirjrotwniata{GnntheT) Joy. Body oblong, snout obtuse, convex, longer than 

 the eye. Eye 4^ in head. Mouth subinferior, small, the upper jaw the longer, max- 

 illary not reaching front of orbit. A black lateral band. Head 4^ j^dejjth 5. D. 8 ; 

 A. 8; scales 6-35-3. Teeth probably 4-4, although only 2-2 are present in one of the 

 typical examples, and none at all in the others ; no evident grinding surface. L. 4 

 inches. Atlisco, Mexico. 



{Graodus nicjrotwniatm Giinther, vii, 4S5 : CJiola nigrotwniata Jordan, Proc. U. S. 

 Nat. Mus. 1879, 226. The accidental loss of the teeth in two of the three typical exam- 

 ples was the occasion of the establishment of the nominal genus Graodvs.) * 



* The reader is advised to be cautious in the use of this key. Some characters ap- 

 pear in the adult only,' and in other cases their presence is a question simply of 

 degree. 



