FISHES 37 



2. Alosa Cuvier. Body elliptical, compressed; jaws toothless; 

 upper jaw with a deep notch at the tip : 3 American species. 



A. sapidissima (Wilson). Shad. Length 750 mm.; head 4.25; 

 depth 3; color bluish above; sides silvery; a dark spot, or a row of 

 several, behind the opercle; gill-rakers 60, very long and slender; rays 

 of dorsal fin 15 ; anal 21 ; scales 60: Atlantic Ocean, Newfoundland to the 

 Carolinas, ascending the streams to spawn; common; introduced into 

 the Pacific Ocean, and very common from San Diego to Fort Wrangel; 

 the most valuable food fish in the eastern States. 



A. alabama Jordan & Evermann. Length 375 mm.; head 4.6; 

 depth 3; color like A. sapidissima; rays of dorsal fin 15; anal 20; scales 

 55: streams entering the Gulf of Mexico. 



A. ohiensis Evermann. Length 375 mm.; head 4.5; depth 3.6; 

 body very long and slender and compressed; rays of dorsal fin 18; anal 

 18: Ohio River at Louisville; rare. 



Suborder 2. Salmonoidei. — Whitefish; salmon; trout. Body 

 elongate, more or less elliptical, covered with cycloid scales; mouth 

 terminal; maxillary, with supplementary maxillary, forming the side of 

 the upper jaw; tail forked; pseudobranchias present; no barbels; lateral 

 line present; air bladder large; pyloric caeca very numerous; posterior 

 dorsal fin adipose: 4 families and numerous species in the fresh waters of 

 the United States. 



Key to the Families of Salmonoidei 



ai Branchiostegals 10 to 20. 



bi Mouth small; upper jaw extending to the eye (Fig. 18). . . .1. Coregonid<z. 



b2 Mouth large; upper jaw extending back of the eye (Fig. 



21) 2. Salmonidce. 



a2 Branchiostegals 6 to 10. 



bi Dorsal fin very long 3. Thymallidfe. 



b2 Dorsal fin short 4. Osmeridce. 



Family i. Coregonidae. — Mouth usually small; the maxillary 

 extending to a point in front of or beneath the anterior border of the 

 eye; dentition feeble; flesh white: 5 genera, i in Arctic America, in 

 lakes and rivers. 



Key to the Genera of Coregonidae in the United States 



ai Lower jaw shorter than the upper; premaxillaries broad, with the 

 cutting edge vertical or directed backwards, 

 bi Gill-rakers long and slender, with 17 to 20 on lower Hmb i. Coregoniis. 



