447 



The common Whitefish is the most important, abundant and widely distri- 

 buted of these. It is distinguished by its compressed body, its elevated back 

 a peculiarity especially marked in the adult arid its small short head with 

 obliquely truncated snout. 



C. quadrilateralis is rounder in body,(it is the Roundfish of Richardson) and' 

 further differs in having a larger head, stouter gill-rakers and a dark-blue colour 

 of the back from the foregoing species, to the size of which it does not reach. Ii> 

 is commoner northward than in the Great Lakes. 



C. Idbradoricus is commoner towards the north-east, as its name suggests", 

 but it is also found in Lake Superior and northward ; it has the compressed body 

 of the common whitefish, but the length of head of the Roundfish. It only 

 attains a length of one foot, and has some teeth on the tongue which the white- 

 fish lacks. A whitefish of similar size occurring in the deeper waters of Lakes Michi- 

 gan and Ontario is known as the Cisco in the former and as the " long-jaw " in 

 the latter ; it is distinguished by the bright silvery color of the under parts, but 

 also by the smaller number of fin-rays (D 10, A 10.) and of the scales in a vertical 

 row. In its larger mouth it approaches the Lake Herring (C. artedi), which 

 occurs in immense shoals in the lakes and especially in Lakes Erie and Ontario, 

 and is, next to the Whitefish, the most important member of the group. The 

 variety known in commerce as the Cisco of Lake Ontario, is a deep water 

 form, much fatter than the ordinary Lake Herring, and bringing as much as one- 

 third higher price on account of its making better kippers than the other. Lastly 

 the Tullibee, which is commoner in Manitoba than in Ontario, is intermediate to a 

 certain extent between the Lake Herring and Whitefish, but has the deep com- 

 pressed body of the latter and scales which, being larger in front and peculiarly 

 marked, are characteristic of this species alone. 



The Whitefish proper deserves special attention on account of its importance 

 from the economical standpoint. As remarked above it exhibits considerable 

 variation both in size and form. The largest fish are taken in Lake Superior, 

 where they may weigh as much as 20 Ib, whereas in Lake Erie they rarely attain 

 to half that weight. The fish are mature when much smaller, the males being 

 conspicuously smaller than the females. 



The observed variations in form are associated with a marked preference for 

 adhering to some particular locality even in large bodies of water. This would 

 seem to be incompatible with the migrations of the fish in the lakes, but it is 

 probable that these movements are from deep into shallow water and vice versa. 

 Fishermen at least are confident that Whitefish taken in different localities can be 

 easily recognized, that those e.g. taken in the upper end of Lake Ontario are 

 different from those in the lower end of Lake Erie; and that the fish e.g. taken in 

 Batchewaung Bay, Lake Superior, are peculiar to that bay. Indians at the Sault 

 say that the Whitefish of the lake above never descend the rapids, while those of 

 the river never ascend to the lake. 



In Lake Ontario and also in the upper lakes, but not in Lake Erie, w^here 

 the water is too warm, two shoreward movements are observed ; the first occurs 

 in June with the approach of warm weather and its object would appear to be 

 the larvae of the various aquatic insects which are then abundant. When the 

 shallow water becomes too warm they retreat again into the deeper, waters of the 

 lake, where the shrimp-like erustaceaof these depths (Mysis relicta and Pontoporeia 

 affinis) furnish them with abundant food. After a stay of two or three months, 

 that is to say till about the middle of October, there begins the second shoreward 

 movement, this time for the purpose of spawning, the spawning grounds being 

 slowly reached towards the middle of November or the beginning of December. 

 After this function has been successfully accomplished they retreat again into 



