FISHES OF COLORADO 121 



TABLE XI 



Number of Native Species in Each Altitddinal Zone 



Below s,ooo to 7,000 to Above 



nrainaiTP DClOW 5,000 10 7,000 10 



"^^^°^se 5,000 Ft. 7>oooFt. 9,000 Ft 



9,000 Ft. 



Platte 24 25 6 4 



Arkansas 14 14 8 6 



Rio Grande S 2 



Colorado 7 8 4 2 



Colorado River Drainage. — This drainage has but nine native 

 species of fish in Colorado, although it includes nearly half of the total 

 area of the state. With the exception of one species all of these are 

 Great Basin forms and peculiar to the Colorado River system; the 

 sculpin, Cottus punctulatus, is a species of the Great Basin streams, but, 

 since it inhabits the small creeks of the high mountains, it is found on 

 both sides of the Continental Divide. The species of the western slope 

 are noteworthy in two respects: with the exception of Yarrow's Dace, 

 Agosia yarrowi, which reaches the length of five inches, all are moder- 

 ately large fishes; and with the exception of the Sculpin, they are 

 species of three of the more primitive families, the Catostomidae, the 

 Cyprinidae and the Salmonidae. 



Drainage east of the Continental Divide and the Sangre de Crista 

 Range. — The Platte and Arkansas rivers, being part of the same major 

 drainage, although separated in Colorado by the Platte- Arkansas 

 Divide, have very similar fish faunas, twelve species occurring in both 

 streams. A comparison is tabulated below. 



TABLE XII 



Native Species in the Platte and Arkansas Rivers in Colorado 



Platte 

 Platte Total Platte Only and 



Arkansas 



28 16 12 5 17 33 9 



Three-fourths of the native species of the state, 33 in all, are found 

 east of the Continental Divide and but one of these, the Sculpin, 

 Cottus punctulatus. is found native on both east and west slopes in 

 Colorado. The Dulcis Minnow, Rhinichthys cataractae dulcis, occurs 

 west of the Divide but has not been taken in western Colorado where 



