APRIL, 1910. FISHES OF CHICAGO MEEK AND HILDEBRAND. 289 



Body elongate, compressed; head pointed, mouth terminal, the 

 lower jaw the longer; interorbital space 5.8 to 6.3 in head; diameter 

 of eye 4.5 to 5.9; snout 4.3 to 5.2; maxillary reaching past middle of 

 orbit, its length 2.2 to 2.4 in head; origin of dorsal fin nearer tip of 

 snout than base of caudal, in front of ventrals; no lateral line; ven- 

 tral scutes 20+13. 



Color silvery to greenish with bluish and golden reflections; back 

 light olive-gray, sides light olive-green, belly opaque, silvery-white. 



Length about 15 inches. 



This fish inhabits the Gulf streams from Florida to Texas, ascend- 

 ing the Mississippi and its larger tributaries to Pennsylvania and 

 Kansas. 



Family Sahnoiiidji'. 



THE SALMON. TROUT AND WHITEFISHES. 



Body oblong or elongate, covered with cycloid scales; head naked; 

 mouth terminal, the maxillaries forming its lateral margins; supple- 

 mental maxillary present; premaxillaries not protractile; adipose 

 fin present ; gill membranes free from the isthmus ; stomach siphonal ; 

 pyloric cceca numerous; air bladder large, with open duct; ova large, 

 falling into the abdominal cavity before exclusion. 



a. Mouth not deeply cleft, the articulation of lower jaws before or 

 under the eye; teeth none or minute; scales moderate, 60 to 95 

 in lateral series. 



b. Mouth small; premaxillary broad, its cutting edge vertical or 

 directed backward; lower jaw the shorter; gill rakers on long 

 limb of first arch fewer than 30. Coregonus, 290 



bb. Mouth larger; premaxillary narrow, its cutting edge nearly 

 horizontal and directed forward; jaws equal or the lower the 

 longer; gill rakers on long limb of first arch more than 35. 



A rgyrosomus , 291 



aa. Mouth deeply cleft; the articulation of the lower jaw behind 

 the eye; strong teeth on jaws, vomer, palatines, and tongue; 

 scales small, more than 100 in the lateral series. 



c. Vomer flat, teeth on shaft in alternating rows or in one zigzag 

 row; body with dark spots. Salmo, 293 



cc. Vomer boat-shaped, the shaft strongly depressed and without 

 teeth; with white or gray spots. Cristivomer, 294 



