UTILIZATION OF DOGFISH 125 



XIII 



The Utilization of Dog-Fish and Selachian Fishes of 



Eastern Canada. 



BY 



James W. Mayor, Ph.D., etc., 

 Union College. Schenectady, N.Y. 



CONTENTS. 



1. Natural History of the Group. 



(a) Characteristics. 



(b) Distribution. 



". The FleSli of selachians with particular reference to its use as food. ^^ 



(rt) The structure of the flesh. 



(b) The chemical composition of selachian muscle. 



(1) As to nutrient value. 



(2) As to urea and ammonia. 



(3) On the physiological effect of urea taken in the food. 



(a) The toxic effect. 



(h) The effect of repeated doses. 



(c) The effect of taking small amounts. 



(c) The palatability of salachian flesh. 



3. The utilization of selachians for purposes other than as food. 



(a) To obtain oil. 



(b) To make glue. 



(c) As a fertilizer. 



(d) Other uses. 



4. The distribution and uses of the common selachians of Eastern Canada. 



5. Literature cited. 



1. NATURAL HISTORY OF THE GROUP. 



(a) CHARACTERISTICS. 



Tlio Selachii'^' form one of the subclasses'-^ of the class Pisces or li.shes and 

 includes dogfishes, sharks, skates and rays. The fishes in this subclass are character- 

 ized by having- a cartilaginous skeleton, the skin either naked or covered with small 

 rough scales or spines, the gill clefts opening separately on the surface of the body and 

 not covered by an operculum, the jaws distinct from the skull and no air bladder. The 

 Canadian representatives are all large marine fishes. 



(h) DISTRIBUTION, MIGRATIONS, ETC. 



Most sharks and dogfishes roam the ocean and have a wide distribution, while 

 most skates and rays live on the sea bottom usually near shore. Probably nearly all 

 sharks and dogfishes show an anadromous migration, living at large in the deei>er 

 waters during late summer and winter and migrating in shoals in the spring and early 

 summer to shallower water, where the young are bom or the eggs doposited, A 

 detailed account of the distribution of the commoner Canadian species will be found in 

 a later section. 



1 Called also Elasmobranchii, Plagiostomata, Chondropterygia, or Placoidei. 



2 In the present paper the classification of Jordan and Evermann ('96) is followed. 



