108 SALMONID.^E. 



head of the vomer is toothless, subpejitagonal, longitudinallj'- elon- 

 gate ; the body of this bone -with a sharp longitudinal ridge, which 

 bears some erect teeth in a single series. Caiidal fin deeply emar- 

 ginate in a specimen 23 inches long, the length of one of the middle 

 rays is two-fifths of that of the longest. There are thirteen scales 

 in a transverse series running from behind the adipose tin obKquely 

 forwards to the lateral line. 



Sides and belly bright silvery, back greenish ; some scattered black 

 spots on the head, body, and dorsal fin. 



Lake Wenern (Sweden). 



There can be no doubt that this is a very distinct species ; the 

 shape of the vomer and the forked caudal fin indicate its affinity to 

 S. salar, but this species has considerably larger scales on the tail ; 

 moreover S. hardinii never enters the sea, being found in the Lake 

 Wenern, into which no marine fish can ascend in consequence of 

 intervening cataracts. A fanciful idea has been started, that it is a 

 Salmon with some of the characters laodified in consequence of its 

 compulsory residence in a freshwater lake. We cannot see how such 

 a change in the life of a fish has the effect of diminishing the size of 

 the scales. Besides, we have no evidence whatever that a migratory 

 species has ever been changed into a non-migratory one ; and persons 

 who bring forward instances of such changes having taken place in 

 the course of a few years, must first prove that they have correctly 

 determined the species of the specimens experimented upon. 



The question whether this fish be not a sterile form of some other 

 species is settled by the observations made by Magister Hardin, who 

 has watched it successively for many years ascending the rivers from 

 the lake for the purpose of spawning. 



It is very doubtful whether this species was known to Artedi and 

 Linnaeus, and whether it ever will be possible to ascertain the Scan- 

 dinavian species to which the latter might have applied the name of 

 S. lacustris ; if he reaUy fixed this name upon a fish known to him 

 from autopsy, he at all events confounded it with the species of 

 Central Europe described by Oesner and his copyists as Trutta la- 

 custris. And as the specific denomination of lacustris has always 

 been retained for the latter, it appears much safer to give a new 

 name to the Wenern fish than to that of Central Europe. The spe- 

 cimen described by Nilsson as Salmo lacustris? agrees very well 

 with that examined by myself. 



a. Female in spirits. Lake Wenern. Purchased of Mr. Wheel- 

 wright. 



Description of this specimen. 



inches. 



Total length 23 



Greatest depth of the body 5 



Length of head 4| 



Girth of the biggest part of the body 12 



Least depth of the tail 1 1 



