MR. F. DAY ON TFTE LOCH-LEVETf TROUT. 



79 



is a most erroneous assertion * ; in tlie one figured as a diagram, 

 which measures 14'6 inches in length, and was 44 months old 

 when caught in October 1886, the knob is very well deve- 

 loped. This knob is constantly seen in all old males of this form ; 

 while even in some old females at Howietoun a small one is 

 occasionally perceptible. 



As to the maxillary bone beinj^ " much narrower and more feeble 

 than in S.fario, in specimens 13 inches long it extends to below 

 the hinder margin of the orbit, and at no age does it reach beyond 

 it" (Giinther), Is this so? This statement as to where the 

 maxillary bone extends posteriorly, first made by Dr. Griinther, 

 is not borne out by an inspection of Howietoun fish, in which in 

 large specimens it extends from one to two diameters of the orbit 

 posterior to the eye, and this is of normal occurrence. In an 

 example 26 inches long it reaches to 1| diameter of the orbit 

 behind the eye ; the longest fish in that establishment having a 

 total length of 27 inches. For as they become more or less 

 sterile at from 8 to 10 years of age, to which breeding males 

 rarely if ever attain, older fishes are not present. 



Doubtless the maxilla and teeth with which it is armed are not 

 so strong at Howietoun as in some (not all) brook-trout of the 

 same size ; and the cause of this feebleness in the jaws, which 

 ceases under altered conditions, is immaterial to discuss, because 

 we have no evidence pointing as to how it first commenced. 

 Although perhaps it may be likened to what is seen in some sea- 

 trout, it may also be observed in many loch-trout in the north 

 of Scotland, with whose jaws I have compared those of the Loch- 

 Leven fishes. The question, in fact, now is, what will be the result 

 on the form and strength of the jaws and teeth when these fishes 

 are transferred to a new locality to battle their own way in the 

 world ? Anyhow, figures of the comparative strength of the jaws 

 in a Loch-Leven female trout and one of the brook-trout of the 



* Since this paper was read, the following observation appeared in the ' Bir- 

 mingham Daily Post' of Dec. 11, illustrating how erroneous statements as to 

 specific differences in species may give rise to a possibly false conclusion : — 

 "The big trout which was recently captured in the Birmingham Corporation 

 Eeservoir at Shustoke has been mounted by Cooper, of London, and may be 

 seen, during next week, at Reeling's fishing-tackle shop, Digbeth. It weighed 

 when caught 8.^ lb., and its length was 27 inches. The formation of the lower 

 jaw shows that it was an old fish, and not one of the Loch-Leven trout with 

 which the reservoir was stocked three years ago." 



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