HYBRIDS— SALMON AND TROUT. 257 



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 surface and passes out at the lower end at tlie same level. This stream rises 

 from springs about half a mile away, and before reaching the octagon pond 

 goes through the two 100 ft. ponds, which are stocked with Lochleven year- 

 lings, consequently anything deleterious in the water must first affect these 

 small fish. 



On one 6| inches long being removed, on Aug. 26th, when it was about twenty- 

 nine months old, it was found to be a female, but sterile. The dorsal fin had 

 three rows of black spots along its lower half. On Nov. 14th, a net was put into 

 this pond, and the specimen 10 inches long, which outwardly looked most likely 

 to prove fertile, removed; it was a sterile male. On Feb. 12th, 1885, one 

 9^ inches long was captured with a fly, to which it rose well. Its dorsal fin was 

 spotted, there were 7 lai-ge black spots on the opercles on the right side, and 8 on 

 those of the left ; a row of red spots along the lateral-line, and a second above it. 

 A slight appearance of par bands was still visible. The fins anteriorly were 

 white edged. 



These fish did not attempt to spring out of the pond until May, 1885, or when 

 thirty-eight months of age, and in a similar manner to smolts when becoming 

 grilse. On May 2-tth, one which was found dead was opened, and proved to be a 

 female with the eggs developing, and which, had it lived, would evidently have 

 bred that winter. 



In June, 1885, the water in the Craigend burn which supplies this pond, became 

 very low, although during that month it never quite ceased flowing. That in the 

 pond became so discoloured, it was impossible to see the fish unless they came to 

 the surface, and their existence could only be demonstrated by throwing a very 

 little food in, when they rose to take it. 



On July 3rd, a slight shower occurred, but rain still held off, and the fish 

 appeared to be livelier than they had been for several days previously, and when 

 fed at 6.30 p.m., some of them jumped quite out of the water at the little food 

 thrown to them. The temperature at the surface was 64°, and experiments made 

 since, show that it is 2° colder at the bottom. On July 4th, at 8.30 a.m., on Mr. 

 Thomjjson, the manager, going to feed these fish, one was observed dead on the 

 surface, while none of the others could be seen to move. The water was at 

 once drawn off, in order to shift any that might chance to be alive, but only 

 two were found to be so, and 142 were dead.* Some appeared as if they had 

 succumbed more than twenty-four hours ; the two which remained alive, subse- 

 quently quite recovered, and were put into another pond. The largest of the 

 hybrids was 13^ inches long, and weighed just over one pound. f 



In both examples the maxilla reached to beneath the hind edge of the eye : 

 there were in one eleven, in the other twelve, rows of scales between the adipose 

 dorsal fin and the lateral-line. Eggs small, but very distinct in both, as if the 

 fish would have bred during the ensuing season ; in no. 2, in which the ova were 

 largest, they measured O'l of an inch in diameter. It should be mentioned that 

 in the 100 foot ponds above the one in which these fish died, none of the 

 Lochleven fry succumbed. 



The cause of this unfortunate termination of a most interesting experiment 

 must probably be sought for in the size of the pond and insufficiency of the 



* Two examples gave the following results : — 



No. 1, No. 2, 



in inches. in inches. 



Length of example . . . 101 . 10- 1 



„ head . . . 1-9 . . 1-8 



,, ,, pectoral fin . . 1-5 . . 1'.5 



„ „ tail . . 1-4 . . 1-3 



„ „ eyes . . . 04 . . 0-375 



Eyes apart . . . . 0-7 . . 0-7 



,, to end of snout . . 0'6 . . 05 



f Mr Thompson observed (July 10th, 1885), that among these dead fish " there were more 

 males than females, I think, but tliere were a good many, I was not quite sure of their sex 

 (apparently barren), as in most hybrids : some bore resemblance to the male parent and some to 

 the female, these last were fattest." 



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