ME. F. DAY ON T FIE LOCH-LEVEN TEOUT. 
79 
is a most erroneous assertion* ; in the one figured as a diagram, 
which measures 146 inches in length, and was 44 months old 
when caught in October 1886, the knob is very well deve- 
loped. This kDob 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 being “ 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” ( Gunther ), Is this so? This statement as to where the 
maxillary bone extends posteriorly, first made by Dr. Gfiinther, 
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 11 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; aud 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 
Reservoir at Shustoke has been mounted by Cooper, of London, and may be 
seen, during next week, at Keeling’s fishing-tackle shop, Digbeth. It weighed 
when caught 8.j- 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.” 
