HYBRIDS— SALMON AND TROUT. 259 



Hybrid between Salmon par and Lochleven trout. 



Day, Proceedings Zool. 800., 1884, pp. 40, 376, and 1886, p. 241. 



November 29tli, 1883. — About 4500 eggs were obtained from a LocMeven trout 

 which, had been hatched early in 1875, and these were milted from a par of the 

 salmon which had been hatched in March, 1881, consequently was 32 months of 

 age, and showed all the par colours. The number of eggs removed as dead 

 during the 78 days they took incubating, were as follows : — December 65, 

 January 18, February 4, or a total of 87 deaths ; while in addition 199 eggs were 

 found to have escaped impregnation. Consequently although the mortality was 

 small, it by no means gave a true index to the result of the experiment, for it 

 was soon perceived that the young were not a strong and vigorous brood, while 

 weak ones are useless for stocking purposes, even should they surmount the 

 diseases and dangers of their youth. 



On February 15th, 1884, some thousands were hatched from these eggs, but 

 nearly all were seen to be sufEering from what has been termed dropsy, or blue 

 swelling of the yeik-sac, probably due to insufficient vitality in their constitutions. 

 On March 12th, 1884, I first saw these young fish, then nearly a month old, and 

 their average length being 0.8 of an inch, but what at once strnck an observer 

 was the large pyriform umbilical sac, which seemed to anchor them to the bottom 

 of the tank. Some were seen singly, others in groups, while every now and then 

 one would start up and swim a short distance in an irregular or spasmodic 

 manner, and then sink to the bottom. This dropsical enlargement in a con- 

 siderable proportion of the fish was 0'35 of an inch in length, and 0'2 of an inch 

 in diameter at its widest part, while it stood out in bolerable relief from the 

 enclosed yelk-sao, showing the existence of two coats, separated one from another 

 by an accumulation of clear fluid. Under a strong glass there appeared to be a 

 want of vitality in the fish, the pulsations being weak, the activity of the heart 

 being feeble, and the blood wanting in red corpuscles. Due to this dropsical 

 distension, the pectoral fins were much impeded in their movements, which is a 

 very material consideration, because in the young fish these fins are in constant 

 motion, in order by keeping up a continuous current to assist the gill-covers in 

 aerating the blood at the gills. June 24th, shifted from the house to the 20-feet 

 pond at Howietoun, close to despatch house ; on August 29th, 1884, about 100 

 were alive. May 6th, 1885, temporarily placed in no. 4 pond, and on June 20th 

 to pond 32, only 53 fish remaining. June 17th, 1886, they were about two dozen 

 in number, and shifted to pond 16, all being small except two, one of which was 

 twelve inches long, and f lb. weight. At this time some had one, others two rows 

 of rather large pinkish-red spots along the lateral-line, and also above and below it. 



On November 23rd, 1886, 1000 eggs obtained from one of these fishes* were 

 milted from a Lochleven trout, and about 700 hatched on Feb. 10th, 1887, or in 

 79 days ; they looked well. June 27th, 667 fish were removed to no. 1 pond at 

 Howietoun, 



Crossing eggs of burn trout with milt from dead par. 



Day, Proceedings Zoological Society, 1884, p. 378. 



November 29th, 1883. — About 1000 eggs taken from a burn trout, S.fario, which 

 had been some years in the pond, were milted from a par 32 months old, which 

 had been a few hours dead. But not a single egg fructified. Only three turned 

 white in December, three in January, and fifteen in February, or a total of 21. 

 On March 12th the remainder were still clear, but without any signs of an embryo 

 within, having evidently been unimpregnated. 



* Length of example, 9-1 inch j length of head, 1-9 inch ; length of pectoral, 14 inch. Lower 

 jaw short. Scales near pectoral fin and along the back to end of dorsal fin very small : eleven 

 rows between adipose dorsal fin and lateral-line. Black spots on the dorsal fin, having a light 

 ring round them : anal with a white front edge. Tail very ragged. 



17 * 



