76 



MR. F. DAT ON THE LOCH-LEVEN TEOUT. 



much longer than the snout, but much narrower and more feeble 

 than in S.fario (see figures, p. 6) ; in specimens 13 inches long 

 it extends to below the hinder margin of the orbit, and at no 

 age does it reach much beyond it ... . The teeth of the body of 

 the vomer form a single series, and are persistent throughout 

 life. Fins well developed, not rounded." He found from 49 to 

 90 caecal appendages. At page 6, I. c, are figured two maxillary 

 bones, stated to be from S. fario and S. levenensis*, but the 

 drawings not being completed at their proximal extremities 

 render it almost impossible to understand what they are intended 

 to represent. The supplementary bone would seem to be where 

 the most difference exists. The same author likewise remarked 

 (p. 7) on the question of species in Salmonidse, and gave his 

 reasons for admitting certain forms to that rank, stating that 

 " whenever the zoologist observes two forms distinguished by 

 peculiarities of organization such as cannot be conceived to be 

 the effects of an internal or external cause, disappearing with 

 the disappearance of that cause, and which forms have been 

 propagated and are being propagated uniformly through all the 

 generations within the limits of our observation, and are yet 

 most probably to be propagated during the existence of mankind, 

 he is obliged to describe these two forms as distinct, and they 

 will commonly be called species." Dr. Giinther has also stated, 

 at a meeting of the Zoological Society, that the late Sir J. 

 Bichardson had informed him that he believed the true Loch- 

 Leven trout had disappeared from that lake. 



In giving a decision on the well-known " Orange-fin " case, in 

 1872, the Sherifi" Substitute found that "in reference to the out- 

 ward silvery appearance of the fish in question, both Dr. Gunther 

 and Professor Young state that the silvery coat with which these 

 fishes is clothed is to be regarded as a distinctive mark of their 

 being migratory fish of the salmon kind. The assumption of the 

 silvery coat .... in the case of river fish, is to be held an almost 

 infallible test of a migratory and sea-going habit. Nor is this 

 inconsistent with the well-known fact, that in the case of certain 

 fish which inhabit lochs having now no communication with the 

 sea, a similar silvery appearance is to be seen. In the case of 



* The teeth in the maxilla of S. levenensis, in Dr. Giinther's figure, are 

 shown as directed forwards and inwards ; the base of each tooth appears as if 

 resting on the skin with its point turned towards the maxillary bone! 



