FISHES. 127 
S. cambricus (Sewin), or S. fario (Common Trout). An 
example of S. ¢utta from the Ouse is in the British 
Museum, and Dr. Giinther has had specimens submitted 
to him from the Esk. 
200. Salmo cambricus Donov. Sewin. 
201. Salmo fario Z. Common Trout. 
Freshwater resident, generally distributed and abundant 
above an elevation of about 250 feet. Below this its 
numbers decrease, and the species becomes local, being 
found in sharp-running streams. As to the quality of 
Yorkshire trout there is considerable variation, even in 
those of contiguous streams presenting no marked physical 
differences. This is exemplified in the case of the rivers 
Aire, Wharfe, and Ribble, which rise in the same district, 
and all of which receive the drainage of the limestone 
plateau on which Malham Tarn is situate. The Tarn 
trout are reputed to be the best in flavour, and only in- 
ferior to the trout of Loch Leven. The Aire trout are 
almost as good, the Ribble trout being ranked next, 
while those of the Wharfe are considered inferior to them 
—the cause of the variation in quality being obscure, 
for there does not seem to be any marked difference in the 
nature of the river-beds. The Malham ova are much in 
request for stocking and improving other streams, and have 
been introduced into the Thames and the Wharfe, but with 
what effect has not been fully ascertained. 
Remarkable malformations are observed in the trout of 
Malham Tarn, and of a beck on the western side of Peny- 
ghent. This is manifested in the former by the deficiency 
of the gill-cover in about one in every fifteen fish caught— 
a calculation based upon a statement with which Mr. 
Walter Morrison has furnished us of the total number 
caught from 1865 to 1880. In the case of the ‘ground 
trout’ of Penyghent, as they are called, Mr. John Foster 
informs us that the malformation consists of a singular 
projection of the under jaw beyond the upper. These 
aberrations are considered to be the result of interbreeding, 
due to an extreme degree of isolation. The isolation of 
Malham Tarn is complete; it has no feeders of sufficient 
size for the introduction of new blood, while the overflow 
is absorbed by fissures in the limestone, after being 
swallowed up by which the water re-appears—as the river 
