1882.] BETWEEN SALMON AND TROUT. 753 



of the longest outer one. The maxilla extends posteriorly to beneath 

 the posterior third of the eye. The preopercle has a distinctly oblique 

 lower limb, which in this example is less strongly marked than in 

 No. 2, while merely a simple curve exists in Nos. 3 and 4. 



The central caudal ray is half the length of the longest outer one 

 in examples 1 and 2, but two thirds in Nos. 3 and 4. Respecting the 

 csecal appendages, Nos. 3 and 4 were first immersed in a weak solution 

 of chromic acid, which has hardened them, facilitating their being 

 counted. No. 3 contained 78, and No. 4 had 61 ; the other two 

 were not examined. If hybrids between the Lochleven Trout and 

 a male Salmon show such variations, it demonstrates the inconstancy 

 of the number of these appendages. We took two Lochleven Trout, 

 each similar in appearance, and about 8 inches in length, which 

 had been bred at Howietoun from eggs and milt of fish inhabiting 

 the stock-ponds, and were consequently one generation removed from 

 Lochleven parentage ; in one they were short and 40 iu number, in 

 the other rather long and 67. (The preparations are on the table.) 



Respecting the scales, from 120 to 121 rows descend from the 

 back to the lateral hue. In Nos. 1, 3, and 4 there are 13 passing 

 downwards and forwards from the hind edge of the base of the 

 adipose dorsal fin to the lateral line, while in No. 2 there are 12. 



Colours. These are nearly identical in all four ; from 12 to 13 lateral 

 parr bauds pass down the sides, which are also more or less closely 

 sprinkled with small black spots and some few red ones ; there are also 

 black spots on the gill-covers and on the upper surface of the head. 

 A very remarkable feature common to all is that the dorsal fin has 

 its front upper edge white, with a black intramargiual band, and 

 from 11 to 13 black spots on or between the rays. Attention may 

 here be directed to no white upper edging existing on the dorsal fin 

 in any of the Lochleven variety of Trout at Howietoun, such a mode 

 of colour being restricted to the burn-trout variety at that estab- 

 lishment ; and this forms another link in the chain of facts that these 

 two forms are merely varieties of one species. 



I wish here to record some experiments commenced on November 

 loth by Sir J. Gibson -Maitland, while I and others were present. 



About 3000 ova were obtained from Lochleven Trout, and fer- 

 tilized with the milt of the American Charr, Sahno fontinalis. They 

 were placed iu hatching-box No. 108. 



About 8000 ova of the American Charr were milted from Loch- 

 leven Trout, and placed in hatching-box No. 104. 



About 9000 ova of the American Charr were fertiUzed with the 

 milt of a Scotch Charr which has been termed Sahno struanensis, 

 and placed in hatching-box No. 115. 



In Austria, observes Peyrer, the Charr (Sahno salvelinus) is crossed 

 with the Trout ; and the young excel the pure breed iu many respects. 

 Whether this is partly due to their being sterile, and consequently 

 not going out of season subsequently to the breeding-season, is not 

 mentioned. The life-history of these true hybrids cannot but be 

 interesting ; and such in due time will doubtless be forthcoming 

 from Howietoun. 



50* 



