1 8 THE FISHES OF OHIO. 



DD. Dorsal fin not as in D. 



P. Dorsal fin single, preceded by free spines ; body scaleless. — 



Gasterosieid.b. 

 PP. Dorsal fins, two ; the first small, composed entirely of spines ; body very 

 slender, covered with scales. — Atherinid.i?. 



II. Ventral Fins Present — Thoracic or Sub-Jugular. 



A. Body covered with scales. 



B. Rays of the ventral fins, I, 5. 



C. Lateral line extending on caudal fin to tip of middle rays.— Sciaenid^s.. 

 CC. Lateral line not extending beyond base of caudal fin. 



D. Pseudobranchise or false gills on under side of opercles well devel- 

 oped ; head scaled forward to between nostrils.— Serranid^e. 

 DD. Pseudobranchiae wanting or covered by skin. 



E. Anal spines, 3 to 10 ; body more or less deep and compressed. — 



Centrarchid.f,. 

 EE. Anal spines, 1 or 2 ; body usually elongate. — Percid.t;. 



BB. Raj-s of the ventral fins not I, 5. 



F. Dorsal fin single, with 3 or 4 spines. — Aphredoderid.e. 



FF. Dorsal fin divided into 2 distinct parts, spines wanting. — Gadid^. 



AA. Body naked ; dorsal fin with 6 or 7 spines. — Cottid^e. 



III. Ventral Fins Entirely Wanting. 



A. Body long and snake-like ; skin cov red with Ion r imbedded scales at right angles- 

 to each other ; lower jaw projecting— Anguillid.?;. 



Series: Ganoidei. 



CHONDROGANOIDEA (The Cartilaginous Ganoids). 



Order: SELACHOSTOMI. 



Family : Polyodontid^E. 



Gemis : Polyodon. 



Polyodon spathula (Walbaum). Paddle-fish ; Spoon-bill Cat. 



A very peculiar looking fish, recognizable at once by its long, paddle- 

 shaped snout, which is about l / 3 the length of the body and is thin and flexi- 

 ble. The eyes are small and placed near the base of the snout ; opercular 

 flap long, reaching back as far as to the ventral fins. Caudal fin large, 

 forked, the lobes about equal. Color olivaceous, paler below. This singular 

 fish attains a length of 5 or 6 feet, but is of little or no economic importance. 



Taken in the Ohio and Muskingum rivers, Kirtland ; "one 

 was taken in a pound net (in Lake Erie) near Vermillion in 

 1874," McCormick ; "common in the Ohio river," Henshall,. 

 1888. 



