1885.] ON RACES AND HYBRIDS AMONG THE SALMONIDiE. 2-41 



8. On Races and Hybrids among the Salmonidse. — Part IV. 



By Francis Day. 



[Eeceived February 17, 1885.] 



In continuation of the series of papers upon " Races and Hybrids 

 among the Salmonidse," 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 re- 

 mained 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 9| inches in length, was in 

 lair 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 conjunc- 

 tion with the largest similarly bred hybrid two years older than this 

 lot, which was found in November 1884 to be merely 16| inches 

 long ^ 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," ^ 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 ■*, which had 

 been reared from eggs hatched at the Howietoun fishery, was on 

 November 7, 1884, when about 100 were obtained by Mr. Thomp- 

 son 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 



3 



Proc. Zool. Soc. 1884, p. 584. =" £ c p 584 



^- "• P' 583. * L. c. p". 582. 



