FISHES. 127 



S. cambricus (Sewin), or S.fario (Common Trout). An 

 example of S. trutta 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 L. 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 



