:30y THE FRESII-WATEU FISHES OF ET'ROPE. 



caudal is more deeply concave ; the pectoral is lonpj'er than the ventral, and 

 both are pointed. The pyloric appendages are stated by Dr. Giinther at from 

 sixty to eighty, tliough Mr. Day finds the range of variation to be between 

 forty-seven and ninety. The number of vertebne does not exceed fifty-nine, 

 and may be one or two fewer. 



The scales are thick and have a ridge in the centre. The number of scales 

 in a transverse series, descending from the adipose fin forward to the lateral 

 line, is thirteen or fourteen. Dr. Parnell })()inted out that focd and season affect 

 the colour and markings of this fisli. 



In the Parr the number of finger-marks on the sides ranges between eleven 

 and fourteen. The flesh is of a deep red. It feeds largely upon fresh- water 

 mollusca. It spawns in the first three months of the year. 



Tliis fish is liable to attacks of fungus, which most frequently affects old 

 males and unspawned females. 



Sir J. Gibson Maitland has reared this species successfully in his ponds at 

 Howictown, and demonstrated that hybrids may be produced between it and 

 various Salmonoids. Mr. Day has described some of these experiments. I^ggs 

 of a four-year-old Loch Leven Trout were fertilised with the milt of Sal mo 

 salar. In three years the fishes which resulted from this cross reached a 

 length of eleven inches. 



The Loch Leven Trout at Ilowietown produces eggs of different sizes, ac- 

 cording to the size of the parent ; and in a seven-year-old fish the bulk of each 

 C:<^g is alx)ut one-seventh greater than in a six-year-old, and there can be no 

 doubt that the larger eggs produce the larger fish, since in ten or eleven months 

 the fry of the older parents were three and a half inches long, and those of the 

 younger parents two and a half inches long ; but poor food may make the 

 eggs small in an old fish. Mr. Day is inclined to regard Loch Leven Trout as 

 derived from the Brook Trout, but suggests the white variety of Salmon 

 Trout as its immediate ancestor. 



Salrao orcadensis (G r nth kr).— Orkney Trout. 



D. 13, A. 11, P. 14, Y. 1). Scales: lat. line 115, transverse -^- 



30. 



There appear to be two races of Trout in the Orkneys, one of which the 

 older writers identified with the Grey Trout {Salii/o eriox), and the other with 

 the Lake Trout [Sd/iiio J'cro.v). One of these, which had previously been re- 

 garded apparently as the Grey Trout, Dr. Ciiinther describes from male 

 specimens twelve inches long, taken in IjocIi Stcnnis. Its affinity to ^S'. 

 nigriplnnu is obvious, but it has a broader and stronger maxillary bone, like 



