78 



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



this is certainly sometimes the case, but sucli a character is not 

 persistent. In the form of the body there is no difference percep- 

 tible in those fish reared in Gloucestershire, as I shall presently 

 show, or at Mr. Andrews's establishment at Guildford, from eggs 

 obtained from Howietoun, and young of brook-trout raised from 

 local brook-trout eggs. As this is the case in fish reared from Loch- 

 Leven eggs it is eyident that their form ultimately depends upon 

 local circumstances or conditions ; for if they are removed to an- 

 other locality where the conditions are different, the brook-trout 

 form is at once seen. The same observations apply to the lengtli 

 of the head, wliich in some well-fed examples, and, in fact, gene- 

 rally in the young raised at Howietoun, is a little shorter in pro- 

 portion to the length of the body than usual in the brook-trout, 

 but this chanofes on their being transferred to a new home. 



As to the length of the rays of the caudal fin * being longer 

 than in the brook-trout, I have been unable to find that such is 

 the case, either in specimens from Howietoun, from Loch Leven, 

 or in those in the British Museum, as they seem to be absolutely 

 identical in the two forms. In a skeleton of a female 20 inches 

 long, I find the middle caudal ray is 2 1 inches in length, and the 

 longest outer ray 2*9 inches ; but were Dr. Glinther's figures, as 

 noted below, to be applicable to these fish, the outer ray should 

 be 4*1 inches in length. Such proportions I have never seen in any 

 of the thousands of these fish I have observed at Howietoun or 

 elsewhere, not omitting those in the British Museum. Specimens 

 having the angle of this fin pointed would appear to be young 

 fish, often males, kept, as at Howietoun, where they are not dis- 

 turbed ; but in the old fishes this fin is invariably rounded at its 

 posterior extremity. 



The statement that the pectoral fin is pointed is partially cor- 

 rect in small specimens, as it also is in small brook-trout, but in 

 old and well-preserved examples it is as rounded as in other 

 races of freshwater trout f. 



As to the male having no knob on the lower jaw, that likewise 



* " In specimens 13 inches loDg, the middle caudal rays are not quite half as 

 long as the outer ones, and in older ones they are half as long." (Giinther.) 

 In a specimen 13^ inches long the middle caudal ray was 1 inch in length and 

 the outer or longest one 1|. 



t In order to demonstrate this, dried examples of the pectoral fin taken from 

 fishes of this race at various ages were shown at the Meeting when the paper 

 was read. 



