526 DESCRIPTION OF COKEGONUS PUSILLUS. 



DESCRIPTION OF COREGONUS PUSILLUS, A NEW SPECIES OF 

 WHITEFISH FROM ALASKA. 



BY TARLKTON II. BEAN. 



Coregonua merki, var. Bean. 



Proc. U. S. Nat, Mas., Vol. iv., 1881, p. 256; Cat. Fish. U. S. Nat. Mus. Fish 

 Exhib., London, 1883, p. 36; Traus. Fish Cult. Assoc, 1884, pp. 34, 39. 

 Coregoiius merki, .Tor. A- GlLB. 



Syu. Fish N. A., 1883, p. 300. 



Not Corc<i<))ius nurkii, Gunther, Cat. Fish. Brit, Mus., VI, 1866, p. 195. 



This small species occurs in northern Alaska from the Yukon River 

 northward. The largest individual we have seen is 11A inches long and 

 was collected in Putnam, or Kuwuk River, Alaska, by Mr. Charles H. 

 Townsend. This example is made the ty T pe of the species. 



I have long doubted the identity of this species witli the merkii of 

 Gunther and am now convinced that the two are distinct. 



The type of Coregonus pusillus has forty-nine long and slender gill- 

 rakers; the eye is nearly one-fourth, maxilla three-tenths, and mandible 

 three-sevenths length of head. The longest dorsal ray is two-thirds 

 length of head ; the head is one-fifth of the total to end of scales. The 

 maxilla does not extend to below the middle of the eye, and the artic- 

 ulation of the mandible is not far behind a vertical through the middle 

 of the eye. The iuterorbital space equals the length of the eye and is 

 somewhat greater than the length of the snout. The longest gill raker 

 is about two thirds as long as the eye. The greatest height of the body 

 slightly exceeds the length of the head ; the least height of the tail is 

 about two-fifths the length of the head. 



The adipose fin is moderately large, its length about equal to the 

 diameter of the eye. The origin of the dorsal is over the twenty-ninth 

 scale of the lateral line, and the ventral origin is under the thirtieth 

 scale. The length of the pectoral equals the length of the head with- 

 out the snout; the length of the ventral is about two-thirds that of the 

 head. The distance from the extended ventral to the vent equals the 

 length of the ventral. The anal origin is under the sixty-second scale 

 of the lateral line ; the length of the anal base equals two-thirds the 

 length of the head and the longest anal ray is one-half as long as the 

 head. The length of the middle caudal rays, from the end of the scales, 

 is one-third of the length of the head and about two-fifths the length 

 of the external rays. 



The dorsal has nine or ten divided rays ; anal eleven or twelve divi- 

 ded rays; ventral I, 11 ; pectoral I, 15; scales 10 — 91 — 9. 



