1G4 CONTRILUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 
The species may be divided as follows :* 
Scales not especially deeper tliaii long; not closely imbricated. 
* Teeth 4-4 ; species of small size. 
t Teeth with grinding surface more or less developed. (Hybopsis Coi^e, non Ag.) 
(a.) Scales in the lateral line more than 45 sailed. 
a. Scales in the lateral line 43 or 44 tiuUtcciia, taurocejdiala, Itamaiura. 
ua. Scales in the lateral line 32-37. 
specirnnmila, nuMa, fretensis, longlrostris, straminea. 
volucella, microstoma, lineolata, missuriensis, procne. 
ft Teeth withont grinding surface. (Cliola.) 
1}. A black spot on anterior edge of dorsal and one at the base of the caudal. 
vigilax. 
1)1). No black spot on anterior edge of dorsal chlora, nigi’otevniata. 
** Teeth two-rowed. 
t Teeth withont grinding surface cohitis, sima. 
H Teeth with grinding surface more or less developed. (Hudsonius Grd.) 
saluclana, sloreriana, hudsonia, eurgopa. 
jii Scales deeper than loug, very closely imbricated along sides of the body. 
* Teeth 4-4. 
t Edges of teeth entire. (Codoma Girard.) 
1: Teeth with grinding surface developed iris, jitgalis. 
tt Teeth withont grinding surface. 
a. Dorsal fin inserted notably behind ventrals ; head very short and blunt, al- 
most round vittata, ornata. 
aa. Dorsal fin inserted directly over ventrals; head moderate, subconic. 
callisema. 
the premaxillary on the level of the pui)il, the maxillary not reaching the front of the 
pupil. Jaws equal. Preorbital large. Scales not closely iml)ricated, 19 in front of 
dorsal fin. Dorsal over ventrals. Caudal peduncle deep. Bluish, sides silvery, 
fins plain. Head 4J ; depth 3f. D. 8 ; A. 8 ; scales 8-46-4 ; teeth 4-4, with narrow 
grinding surface. Lake Tnpataro, Guanajuato. 
{Hudsonius altus Jordan, Proc. U. S. Nat. Mus. 1879, 301.) 
(5.) C. sailed (Gunther) J. & G. Caudal peduncle not quite twice as long as deep. 
No barbels. Snout obtusely conical, longer than the eye, Avhich is one-fifth the length 
of head. Upper jaw slightly overlapping the lower. Maxillary not extending to eye. 
Dorsal immediately behind ventrals. Fins short. Brownish green above, minutely 
dotted V7ith black along the sides. Head 4 ; depth 3|-. D. 7 ; A. 6 ; Lat. 1. 54 : teeth 
4-4, long, curved, with grinding surface. Intestinal canal with few convolutions. 
L. 34 inches. Cuernavaca, Mexico. {Giinther.) 
(Ceraticlithgs salleei Giinther, vii, 484: Hudsonius sailed Jordan, Proc. U. S. Nat. Mns. 
1 d79, 226.) 
(c.) C. nigrotaaiieiia (GiintheT) Jov. Body oblong, snout obtuse, convex, longer than 
the eye. Eye 4^ in head. Month snbinferior, small, the upper jaw the longer, max- 
illary not reaching front of orbit. A black lateral baud. Head 44; dei)th 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. 
{Graodm nigrotevnieetus Giinther, vii, 485: Cliola nigrotecniafa Jordan, Proc. U. S. 
Nat. Mus. 1879, 226. The accidental loss of the teeth in two f)f the three typical exam- 
ples was the occasion of the establishment of the nominal genus Graoelus.) 
* 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. 
