GREAT LAKES COREGONIDS 



515 



mesh to gill any but extreme examples — namely, the 4}/£-inch whitefish nets. Some 

 nets of 2}4, and 2% inch mesh were set by me on July 26, 1922, off the source of the 

 Nipigon River in 10 to 15 fathoms (record 10) and took 11 individuals along with 129 

 other Leucichthys, and a set made on July 28, 1922, off Macdiarmid in 30 fathoms 

 (record 1) took only 3* out of 251. The same nets set on July 28, 1922, off Livingston 

 Point in 56 fathoms took no individuals of the species. What data we have, there- 

 fore, indicate that the species is found in shallow water during the summer, at least. 

 Dymond (1926) also suggests that it is a shallow-water form. 



BREEDING HABITS 



Nothing is known about the breeding habits of the species. None of the speci- 

 mens taken from July to October showed sexual glands either ripe or recently spent, 

 so that the spawning season must fall later than October and earlier than July. 



Genus COREGONUS Linnaeus 



The Great Lakes fish of the genus are relatively large. They are usually imma- 

 ture under 2 pounds and attain a weight of more than 20 pounds. The body is 

 compressed laterally; its width is equal to about 50 per cent of its depth. The pre- 

 maxillaries are wider (dorsal-ventral measurement) than long and retrorse in position. 



a b 



Fig. 27.— Openings of a nostril in Prosopium (A) and in Coregonus (b) 



The two openings of each nostril are separated by two flaps. (Fig. 27.) The exposed 

 area of the scales of the lateral line is not conspicuously smaller than that of those of 

 the adjacent rows. The gill rakers on the first branchial arch are usually less than 32 

 and more than 20. Vestigial teeth are usually present on the premaxillaries, pala- 

 tines, mandible, and tongue. The prefrontal bone is moderately developed, more 

 than in Prosopium but less than in Leucichthys. The carina of the frontals extends 

 to the frontal-parietal suture. 



COREGONUS CLUPEAFORMIS Mitchill 



The Whitefish (Fig. 29) 

 Salmo clupeaformis Mitchill, 1818, p. 321, Sault Ste. Marie. 



Coregonus clupeiformis Evermann and Smith, 1896, pp. 297-301, pi. 17, Great Lakes. 



Coregonus clupeaformis Jordan and Evermann, 1911, pp. 35-37, fig. 19, PI. VI, Great Lakes, except 



Erie; Dymond, 1926, pp. 55-57, Lake Nipigon. 

 Salmo otsego Clinton, 1822, pp. 1-6, fig., Otsego Lake. 



Coregonus labradoricus Richardson, Evermann and Smith, 1896, pp. 302-305, pi. 19, Great Lakes- 



probably also Richardson, 1836, Labrador. 

 Coregonus sapidissimus Agassiz, 1850, pp. 344-348, Lake Superior. 

 Coregonus latior Agassiz, 1850, pp. 348-351, Lake Superior. 

 Coregonus neo-Hantoniensis Prescott, 1851, p. 343, Lake Winnepesaukee. 



Coregonus albus LeSueur, Jordan and Evermann, 1911, pp. 37-38, Pi. VI, Lakes Erie and St. Clair 

 not of LeSueur, 1818. 



