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Show 1885.] ON RACES AND HYBRIDS AMONG THE SALMONIDJK. 241 8. On Races and Hybrids among the Salmonidse.-Part IV. By FRANCIS DAY. [Received February 17, 1885.] In continuation of the series of papers upon " Races and Hybrids among the Salmonidae," which I have communicated to this Society, I propose to resume my account of the Howietoun experiments from November 1884 until the present time. This period has been most instructive, as comprising the period during which the ova of the hybrids have been incubating ; it has also demonstrated that we must not be too confident, should the eggs of two-year-old fish fail to hatch, that such failure is not due to the immaturity of the parents. Respecting the hybrids between the Lochleven-Trout eggs and Salmon-smolt made December 24, 1881, those fish which have remained in the Octagon pond at Craigend * do not appear to have bred, neither have they much increased in size. On February 12 one was taken with a fly : it measured 9g inches in length, was in fair condition, and on being opened proved to be a barren male. Its form was similar to what I have previously described these fish to be. There were seven large black spots on the opercles on the right side and eight on those of the left; a row of red spots along the lateral line and a second series above it. Fins edged anteriorly with white, the dorsal with several irregular rows of black spots. A slight appearance of par-bands when in certain lights. Taken in conjunction with the largest similarly bred hybrid two years older than this lot, which was found in November 1884 to be merely 16^ inches long2, the supposition is raised that the breed may be a dwarfed one. The young hatched in 1884 from Lochleven-Trout eggs and young Salmon-par, which produced " dropsies," 3 are still in one of the large boxes at Howietoun. The water was too discoloured to allow of their being visible: a few were obtained by means of a landing-net; but they do not appear to have much increased in size. The first experiment made with the eggs of a Grilse 4, which had been reared from eggs hatched at the Howietoun fishery, was on November 7, 1884, when about 100 were obtained by Mr. Thompson from one of these fish that had jumped out of the pond, and which were milted from a Lochleven Trout. On January 3, 1885, 18 hatched; and when I saw them on February 10 they were looking very well, and none of them appeared to be suffering from any deformities. Particular attention must be drawn in this place to the age of the Grilse, which had been hatched early in 1881 from ova and milt obtained from the Teith in December 1880. The fact of these young fish being in their third winter season has probably much influence on the success of their hatching. Prior to discussing the results of incubation in the ova of the 1 Proc. Zool. Soc. 1884, p. 584. 2 L. c. p. 584 3 L. c. p. 583. * L. c. p. 582. |
