THE ORIGIN OF VARIETIES IN SALMONID. 137 
of Derry, in the River Glenlark, in the Munterloney Mountains, 
we are told by Thompson that the water and stones are deeply 
tinged with a rust colour, of which the Trout likewise partake. 
Their flesh is very inferior, and of a metallic flavour—so bad are 
they that the country people will not eat them. 
Lastly, as to colour, we have the Salmo nigripinnis, or “ Black- 
finned Trout.” Were this simply considered a new species from 
its colour some curious questions might arise. Thus, in an 
excellent article upon ‘‘ The Brown Trout introduced into Otago,” 
by Mr. Arthur, in the ‘ Transactions of the New Zealand Institute’ 
for 1878, he observes that in the ‘‘ Water of Leith,” when first 
opened for fishing, the Trout were of a fine appearance, colours 
being bright and the red spots large, but there is a falling off in 
this respect, at least as regards average-sized fish, and during 
spawning they all assume a darker or greyish hue. Collecting 
the results of an examination of various specimens, Mr. Arthur 
found that the number of rays varied in some of the fins, while 
the number of black or red spots was by no means constant, and 
although the best known British authors give the ccecal appendages 
at from thirty-three to forty-seven, he found them in Otago to be 
from forty-three to fifty-four, thus opening up another subject 
respecting Trout upon which I do not at present propose to 
enter. Still, I may just remark that if the number of these 
appendages becomes increased owing to change of climate, they 
must be looked upon with great suspicion as modes of designating 
species. Many other curious local changes are pointed out as 
having been induced in the transplanted fish—thus even the 
shape of the preopercle varies. 
In conclusion I must again express a hope that a strict watch 
will be kept on introduced forms. I have been told that 
S. fontinalis, both in the Wandle and Cardiganshire, has interbred 
with the Common Trout. A very minute and exhaustive investi- 
gation in such cases would be exceedingly interesting, and such I 
hope will be furnished during the present year. 
