THE COMMON TROUT 261 
as to appear creatures of totally distinct species. Fatio, 
writing about the trouts of Central Europe, observes: ‘“ The 
little brook-trout which most zoologists distinguish under the 
name of Salmo Ausonii is truly, in my opinion, nothing more 
than a form of the great trout of our lakes, which is called, 
according to circumstances, Trutta lacustris, Trutta Schiffer 
Miuilleri, Fario Marsiglii, or Salmo lemanus. Most of the 
characters proposed for its distinction are those of the early 
age of the fish. In a small stream the trout, which cannot 
grow for want of room, arrives at an advanced age, retaining 
more or less of the character of infancy.” 
Even so in this country. Taking two lakes in Central 
Scotland within four miles of each other in the forest of 
Corrour—Loch Ossian, a little more than three miles long, 
and Loch Treig, about seven miles long—we find the most 
striking contrast in their trout population. No salmon or 
migratory sea-trout obtain access to one or other. Loch 
Ossian is comparatively shallow, and swarms with small trout 
about six or eight to the pound. You may fill a barrow with 
them by fly-fishing on a mild day, and never get one weighing 
more than a quarter of a pound. Moreover, every fish retains 
the juvenile parr-markings, and the flesh is white or lightly 
tinged with pink. The food supply of the lake being a fixed 
quantity, it has to be sub-divided among millions of mouths, 
whence it comes that the trout of the lake are all dwarfs. It is 
very different in Loch Treig, which is of immense depth— 
one of the requisites indispensable to the production of that 
class of trout which Dr. Giinther distinguishes as the Great 
Lake Trout of North Britain, Wales, and Ireland (Sa/mo ferox). 
Ferox of great size inhabit Loch Treig, and the rest of 
the trout therein are goodly fish, running commonly from 
4 Ib. to 2 lb. I “say the rest of the trout”; but who is to 
declare which are ferox and which are fario? Is it a question 
of size? Then I ask the reader to what species does he assign 
the great silvery trout of the Thames, running up to 12 |b. 
