XXI MALACOPTERYGII 567 
represented in the seas and freshwaters of Europe, Asia, and 
North America, extending southwards to North-West Africa, 
Asia Minor, Northern Persia, the Hindu Kush, the head of the 
Gulf of California, and the Rio Grande ; Salvelinus, Charr, with 
8 to 10 rays in the anal, and teeth on the raised head of the 
yomer only, of the lakes of Northern and Central Europe and the 
rivers of the northern parts of Asia and North America as far 
north as 82° 34’, sometimes descending to the sea. 
The changes in form and colour which these fishes undergo 
when passing from fresh water into the sea or when artificially 
transported from one place to another are very great, and this 
plasticity, together with the connecting links which render the 
naming of not a few specimens impossible, have caused most recent 
students of the genus Salmo, in Europe at least, to reduce many 
Fic. 343.—Trout (Salmo trutta). x4. (After Valenciennes. ) 
of the so-called species to the rank of local varieties, and even 
our common Brown Trout or Brook Trout (S. fario) is now 
generally regarded as not specifically separable from the ana- 
dromous Sea Trout (S. trutta). The anadromous true Salmon 
(S. salar) may be distinguished by its somewhat larger scales, 
there being only 11 or 12 in a transverse series running from 
the posterior border of the adipose fin forwards to the lateral 
line, Trout having 13 to 16. The Charr of the lakes of Wales, 
the North of England, Scotland, and Ireland are also regarded 
as mere varieties of the common Northern migratory Charr 
(S. alpinus), of which the “ Omble Chevalier” of the Swiss lakes 
and the “Saeblings” of the Alpine lakes of Germany and Austria 
are likewise varieties. An allied species (S. fontinalis) has been 
introduced into England from North America, as well as a true 
Trout (S. irideus). The large size of the eggs, their lack of 
