GREAT LAKES COREGONIDS 



299 



teeth on vomer and tongue, when present, in several series; scales larger, 13 or less 

 in a transverse series from the origin of the dorsal fin to the lateral line." Regan 

 recognized four genera — Stenodus, Coregonus, Phylogephyra, and Thymallus. 

 Coregonus is distinguished from the others chiefly by having no teeth or vestigial 

 ones. In agreement with Cope recent American writers have accepted the family 

 Coregonidae, and I follow current American practice in this paper. 



The genus Coregonus, as recognized by Regan and most other European ich- 

 thyologists, includes all the known species of whitefish and lake herring, but certain 

 American ichthyologists have recognized several minor groups of species and have 

 given them generic or subgeneric names. Thus, the lake herrings are placed by 

 Jordan and Evermann (1911) in the genus Leucichthys under three subgenera, 

 Thrissomimus, Cisco, and Allosomus, while the whitefishes are placed in the genus 

 Coregonus under the subgenera Coregonus and Prosopium. For reasons to be given 

 later, I do not find their arrangement satisfactory. I hold the three groups 

 Leucichthys, Coregonus, and Prosopium as distinct genera and disregard the sub- 

 genera of Leucichthys. 



The genus Coregonus of the Europeans, which is approximately the family Core- 

 gonidae of Americans, has an almost completely circumpolar distribution. (See 

 fig. 1.) The various species occur in rivers, lakes, or in the ocean. Certain Sibe- 

 rian species spend most of their life in the Arctic Ocean but ascend rivers periodically; 

 while others, notably the Scandinavian species albula and lavaretus and the American 

 quadrilaterale, are supposed to occur in lakes, rivers, and in the sea. Most of the 

 recognized species, however, are confined to inland lakes. 



STATEMENT OF THE PROBLEM 



Wherever they occur, the coregonids, like the salmonids, are important food 

 fishes; but probably nowhere else do they attain so much importance in the fisheries 

 as in the region of the Great Lakes. In view of the great importance of these fisheries 

 it is desirable, from a purely economic point of view, to determine what forms are 

 found in the various lakes of the region and to obtain full knowledge of the natural 

 history of these forms and of the conditions under which they live. Without such 

 knowledge any legislative or fish-cultural steps designed to conserve the fisheries 

 concerned must be unintelligent in character and their success must be a matter of 

 chance. The present investigation had as its object the determination of the forms 

 of coregonid fishes that occur in these lakes and the collection of data on their natural 

 history. In addition to its economic significance, the problem is one of scientific 

 interest. It concerns not merely the ecology of the Great Lakes species but it involves 

 also the ultimate consideration of their origin and evolution and of their relationships 

 with one another and with the coregonids of Asia and Europe, as well as with those 

 of other parts of America. 



SOURCE OF MATERIAL AND DATA 

 THE GREAT LAKES 



This investigation of the systematic relationships and the natural history of the 

 coregonids was begun on Lake Huron for several reasons. Inasmuch as this lake, 

 together with the North Channel and Georgian Bay, presents a maximum differentia- 



