10 PRELIMINARY REPORT 



Class PISCES. The True Fishes. 

 KEY TO THE FAMILIES OF PISCES. 



A. Vental fins present, abdominal. 



B. Dorsal fins two, the anterior rayed, the posterior adipose. 



C. Body not covered with scales; head with four to eight 



barbels; dorsal and pectoral fins with a stout spine. 



(Cat-fishes) Siliirirtpe, 15 

 CC. Body covered with scales and without barbels or 

 spines. 

 D. Head not covered with scales; maxillary bones 

 distinct. 

 E. Scales ctenoid; margin of the upper jaw 

 formed by the premaxillaries alone. 



(Trout-perches) Percopsiclae, 52 

 EE. Scales cycloid; maxillary bones forming a 

 part of the upper jaw ; stomach with many 

 pyloric caeca. (White Fish, Trout) Salmonidpe, 43 

 BB. Dorsal fin single, preceded by several unconnected spines; 



very small fishes. . . (Sticklebacks) Gasterosteidse, 51 

 BBB. Dorsal fins two, the anterior of three to eight spines; the 

 posterior of soft rays; anal spine one. 



(Silversides) Atlierinidae, 53 

 BBBB. Dorsal fin one, composed of soft rays only. 



C. Tail with spinal column ending in its upper portion 

 (heterocercal). 

 D. Caudal fin forked. 



E. Snout long, broad and shovel-like, nearly 

 one-half the length of the body. Body 

 naked. . (Paddle Fishes) Polyodontidfe, 12 

 EE. Snout shorter; body covered with bony 



shields. . (Sturgeons) Acipenseridae, 12 



DD. Caudal fin not forked. 



E. Jaws long, the sharp teeth conspicuous. 



(Gar-fishes) Lepisosteidae, 14 

 EE. Jaws short, head thick; dorsal fin long. 



(Dog-fish) Aiuiid?e, 15 

 CC. Tail with the spinal column ending in its center, 

 lobes equal (homocercal). 

 D. Scales cycloid. 

 E. Head scaly. 



F. Upper Jaw not protractile; its posterior 

 edge formed by the maxillaries. 

 G. Teeth unequal, coarse and sharp. 

 (Pikes; called pickerels in Minnesota) Luciidae, 48 

 GG. Teeth equal, weak and set close to 



each other. (Mud Minnows) Umbrida^, 48 



