76 
MR. E. DAT ON THE LOCH-LEYEN TROUT. 
much longer than the snout, but much narrower and more feeble 
than in S.fario (see figures, p. 6); in specimens 13 inches loDg 
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. Tins well developed, not rounded.” He found from 49 to 
90 csecal appendages. At page 6, l. 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 Sahnonidse, 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. Gunther has also stated, 
at a meeting of the Zoological Society, that the late Sir J. 
Dichardson 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 Sheriff Substitute found that “ in reference to the out- 
ward silvery appearance of the fish in question, both Dr. Giinther 
and Professor Toung 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. Giintlier’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! 
