PERCHES. 67 



nearly the same hues as the parts from which they 

 respectively arise ; but the caudal, the anal, and 

 the ventrals have their rays of the most brilliant 

 scarlet, especially the latter, and the membranes are 

 tinged with the same hue. The iris of the eye 

 is golden. The lateral line is distinct, running 

 in a slightly arching line from the gill-flap to the 

 tail- fin. 



Mr. Yarrell mentions, as having been found in 

 the waters of particular soils, specimens of the 

 Perch almost entirely w^hite ; and others of an 

 uniform slate-grey hue with a silvery appearance. 

 The latter variety is obtained in the ponds of 

 Ravenfield Park, in Yorkshire, and is found to 

 retain its peculiarity of colour, when transferred 

 from its native ponds to other waters. 



Yet another variation of hue, associated with 

 another curious peculiarity, is ascribed to the 

 Perch of Malham, or Maum Tarn, in Yorkshire, 

 by Hartley, the author of an account of some 

 natural curiosities of that neighbourhood. Speak- 

 ing of these fishes, he says, '' There is certainly 

 a very extraordinary phenomenon attending them, 

 the cause of which I leave to naturalists to ascer- 

 tain. After a certain age they become blind : a 

 hard, thick, yellow film covers the whole surface 

 of the eye, and renders the sight totally obscured. 

 When this is the case, the fish generally are 

 exceedingly black ; and although, from the more 

 extreme toughness and consistency of. the mem- 

 brane, it is evident that some have been much 

 longer in this state than others, yet there appears 

 no difi"erence either in their flavour or condition. 

 Perch of five pounds' weight and more have been 

 taken. They are only to be caught with a net ; 



