Family Salmonidae 



JOHN R. DYMOND 



University of Toronto 



Acknowledgment. I am indebted to Henry B. Bigelow for much help in the prepara- 

 tion of the manuscript, especially concerning conditions in New England and in the 

 matter of angling. 



Characters. Mouth large. Maxillary reaching to a vertical through the eye or 

 beyond. Teeth well developed on jaws, vomer, palatines, and in a double series on the 

 tongue. Parietals not meeting in the midline. Orbitosphenoid, Basisphenoid, and 

 SuPRAOPERCuLAR present. Last few Vertebrae upturned. Dorsal fin with not more 

 than 1 6 rays, 12 or less of them branched. Adipose dorsal fin present. Axillary 

 PROCESS associated with ventral fin. Swim bladder connected to alimentary canal 

 by a permanently open duct. Oviducts incomplete, being represented by a fold of 

 the peritoneum. Stomach with Pyloric caeca. 



Sexual Dimorphism. This phenomenon occurs in the entire family, especially at 

 spawning time, with an extreme condition in Oncorhynchus to comparatively little in 

 Cristivomer, Salmo occupying an intermediate position. The extent to which these changes 

 affect the two sexes is discussed in the account of the Atlantic Salmon (p. 463). 



Remarks. For characters that separate the family Salmonidae from other families 

 of the Suborder, see Key to Families (p. 456) and related text. 



Range. The Salmonidae, composed of six genera, is an important and widely 

 distributed family of the Arctic and north temperate zones of the northern hemi- 

 sphere. Many members are anadromous, living in both fresh and salt water, and 

 others are confined to only freshwater lakes and rivers (see Key to Genera, p. 458). 

 The species of Salvelinus and Salmo are found in both marine and fresh waters of 

 northern North America, Europe, anei Asia. The various species of Oncorhynchus are 

 confined primarily to the Pacific, but one or two species range through the Bering 

 Strait and then for limited distances eastward and westward along the Arctic coasts of 

 North America and Asia. Three genera are virtually confined to fresh water: Cristi- 

 vomer of North America, Brachymystax of Asia, and Hucho of Europe and Asia; being 



457 



