April, I9IO. Fishes of Chicago — Meek and Hildebrand. 229 



jj. Body without scales; ventral fins each of one spine and one 

 soft ray; dorsal fin with 2 or more spines not connected by a 

 membrane. G aster osteidcB, 302 



ii. Scales ctenoid their free edges rough; dorsal fins 2, the posterior 

 adipose. Percopsidce, 303 



hh. Ventral fins composed of one spine and 5 soft rays; anterior 

 dorsal fin of 4 to 10 spines connected by a membrane; body 

 gQg^ly_ AtherinidcB, 304 



bb. Ventral fins thoracic or jugular. 



t. Ventral rays of one spine and 6 or 7 soft rays; vent before 

 pectoral fins. Aphredoderidcs, 305 



tt. Ventral rays not more than one spine and 5 soft rays. 



u. Chin without a barbel; soft dorsal fin of less than 40 rays; ven- 

 tral fins below or behind pectorals. 



V. Body covered with true scales. 



w. Lateral line not extending on the caudal fin ; soft dorsal of less 

 than 25 rays; jaws with teeth. 



X. Spinous and soft dorsal fins united into one fin, the spinous por- 

 tion lower than soft portion ; preopercle usually not serrate. 



CentrarchidcB, 306 



XX. Dorsal fins separate or very sHghtly joined; the fins of about 

 equal height. 

 y. Anal fin with i or 2 spines. Percidce, 317 



yy. Anal fin with 3 spines. SerranidcE, 332 



WW. Lateral line extending on the caudal fin; soft dorsal of more 



than 25 rays; jaws without teeth. Sciaenidcs, 334 



vv. Body without true scales; more or less armed with prickles or a 

 few scale-like plates ; cheeks with a bony stay ; ventral rays of 

 one spine and 3 or 4 soft rays. Cottida, 335 



uu. Chin with a barbel; soft dorsal fin composed of more than 

 40 rays. GadidcE, 338 



