42 TELEOSTEI : EVENTOGNATHI. — XII. 



o. Pectoral spines moderate, the inner serrae weak, not half diameter of 

 spine, the outer stronger, retrorse, body elongate ; coloration nearly 

 uniform, the fins darker edged. 

 d. Pectoral spine short and weak, ahout 3 in head in adult. 



61. N. ezllis Nelson. Head small, rather narrow, depressed, 4 

 in length ; depth 6 ; pectoral spine retrorse-serrate without, with 6 

 small teeth within ; humeral process obscure ; jaws subequal. A. 

 14 to 1 7. L. 4. Wis. to Kansas. (iV. elassochir Swain & Kalb.) 

 (Lat., slim.) 



dd. Pectoral spine longer, about 2 (1|^ to 2^) in head. 



62. N. insignls (Richardson). Head rather broad, flat and 

 thin, the upper jaw projecting; head 4^; depth 6. A. 14 to 16. 

 L. 10. Pa. to S. C, common E. (Lat., remarkable). 



cc. Pectoral spine very strong, curved, more than half head, its posterior 

 serraB recurved, their length about equal to diameter of spine, the 

 anterior serrse small, 

 e. Color much variegated; adipose fin deeply notched, but not separated 

 from C. 



63. N. miurus Jordan. Grayish ; top of head, tip of dorsal, 

 middle of adipose fin, and caudal black, the body with four black 

 cross-blotches ; head not specially depressed eye 4^ in head ; hu- 

 meral process moderate ; pectoral spine 1 J to 1^ in head ; head 3|. 

 A. 13 to 15. L. 5. E. N. C. to Minn, and La., abundant, (jutt- 

 ovpos, curtailed.) 



ee. Color nearly plain brownish, everywhere above covered with fine 

 small dots ; adipose fin almost or quite free from caudal. 



64. N. eleutherus Jordan. Head broad, flat, depressed, the 

 form very much as in Leptops olivaris ; humeral process obscure ; 

 eye 5^ in head; pectoral spine l^ to 2 in head; head 3|; A. 13. 

 L. 4. White R., Ind., and French Broad R.; 3 specimens known. 

 (f\fv6epos, free.) 



66. Pectoral spine entire, grooved behind; adipose fin continuous with 

 the caudal. 



65. N. gyrinus (Mitchill). Head short, broad and deep; pecto- 

 ral spine 2 in head ; jaws subequal, yellowish brown, not blotched, 

 but with a narrow black lateral streak, sometimes with two above 

 it. A. 15 or 16. L. 5. Hudson R. to Minn, and La., common N. 

 {yvptvos, tadpole.) 



Order XII. EVENTOGNATHI. (The Plectospondt- 

 Lous Fishes.) 



This group, defined on page 26, contains the great majority of 

 the fresh-water fishes of the world. Its essential character is in 

 the modification of the anterior vertebrae, as in the Nematognathi, 



