160 SALMON AND TROUT. 
river has at this point a bed of gravel, whilst the tarns are 
floored with a deep deposit of bog mud. A similar peculiarity 
has been noticed as regards the black-moss trout of Loch 
Knitching ; and Loch Katrine produces a small description of 
very dark trout, which probably owe their discolouration, as in 
many other lochs, to the drainage of the bog moors. 
Even on different sides of the same river I have found 
complete differences in the colour and also in the edible quali- 
ties of the trout, depending on the nature of the bottom soil ; 
and a similar example, in the case of the fish of a small Irish 
lake in the county of Monaghan, is mentioned by the author 
of ‘Wild Sports of the West.’ One shore was ‘ bounded by a 
bog, the other by a dry gravelly surface. On the bog side the 
trout are of the dark and shapeless species peculiar to “moorish” 
loughs, whilst the other affords the beautiful and sprightly 
variety generally inhabiting rapid and sandy streams. Narrow 
as the lake is, the fish appear to confine themselves to their 
respective limits—the ved trout being never found upon the 
bog moiety of the lake, nor the d/ack where the under surface 
is hard gravel.’ 
Notwithstanding, however, this almost infinite range of 
variety in the yellow trout, depending upon local circumstances 
of food, &c., we have only one really distinct species common 
to both running and still waters, viz. Salmo fario, and one in- 
digenous to lakes and similar situations, viz. the great lake 
trout, Salmo ferox. 
Dr. Giinther, of the British Museum, has ‘recognised’ 
another separate species in the well-known Loch Leven trout 
of Scotland, to which he gives the name of Salmo levenensis.! I 
1 The Loch Leven trout spawn in January, February, and March. I have 
had opportunities of examining many specimens of the Loch Leven trout, and 
their characters agreed closely with those given by Dr. Parnell from a specimen 
one foot in length. Of these the principal were: 
Head a little more than one-fifth of the whole length, tail fin included. Depth of 
body at the deepest part about equal to length of head. Gill cover produced behind; 
lower margin of operculum oblique ; pre-operculum rounded ; end of the superior maxil- 
lary bone extending as far back as the hinder margin of the orbit. Commencement of 
back fin half-way between point of upper jaw and a point a little beyond the fleshy 
portion of the tail, End of back fin even, sometimes concave. Pectoral fins pointed 
