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DEPARTMENT OF THE NAVAL SERVICE 



cent) and the body relatively stout. At Acadia station 38, individuals as long as 

 22mm. were obtained, and those as long as 15mm. were immature. The jaws were 

 more numerous in these (7-10), the tail proportion larger (25-32 per cent), and the 

 body more slender. If these are one species, the differences in structure will be due 

 to the differences in the conditions under which they have developed. These hifFer- 

 ences are similar to those seen in the varieties of S. elegans (see -under that species) 

 occurring in localities where different climatic conditions prevail. In both the cold 

 water develops a type of larger size, with more jaws, and a higher tail percentage. 

 The number of jaws increases with age (there may be latterly a decrease) and the 

 maximum number in the cold-water type is higher than is found in the warm-water 

 type (though the difference is not great). The following are the numbers of jaws 

 found in the two types : — 



Tropical water. ("Acadia" Station 75). 



Boreal Water. ('"Acadia" Stations 17, 38, and 85). 



