28 MR. F. DAY ON RACES AND [JaU. 15, 



individuals of whatever size, but, as far as our experience reaches, is 

 even often characteristic of the species of a genus" 1 . Likewise, in 

 his 'Introduction to the Study of Fishes,' 1880, p. 159, he ob- 

 serves, " The ova of Teleosteous Fishes are extremely variable in size, 

 quite independently of the size of the parent species. The ova of 

 large and small individuals of the same species, of course, do not differ 

 in size." 



This brings us to the consideration of whether it is possible that 

 increased size of eggs may lead to augmented size of offspring, 

 irrespective of the question of changing the locality they inhabit, or 

 increasing the space or amount of water in which they reside. 



The following interesting experiment was instituted fourteen 

 months since by Sir James Maitland. Two batches of Lochleven 

 Trout were spanned in the winter of 1882 on November 2nd, the 

 parents of one having been hatched in 1875, and of the other in 

 18/b". The eggs were similarly treated, and hatched in January and 

 February 1883. 



In the garden in front of Sir J. Maitland's house at Craigend two 

 ponds have been constructed for the reception of young rish, each of 

 the same width and 100 feet long ; one is nearly on a level with the 

 other, and the same stream runs through each. Into these ponds 

 the two lots of fry were turned — those from the older or 1875, or 

 seven years' old parents, having the lower pond ; those from the 

 younger or 1876, or six years' old parents, having the upper pond, 

 while they were fed and treated in an identical manner. 



On November 29th we examined these two ponds, the fry in the 

 upper of which, or from the younger parents, seemed to average 

 about 2£ inches in length, while those in the lower pond appeared 

 to average about 3| inches in length ; showing that from the eggs 

 of the older parents had emanated the more satisfactory offspring. 



We next proceeded to draw a net through each pond ; and I selected 

 three young fish from the upper and five from the lower series as 

 among the finest examples of each batch. These fish gave the 

 following results : — 



Upper pond, from 18 "6 parents. 



Length. Bars. Bars. 



inches. 



3-5 13 13 



3-0 13 12 



2-9 14 13 



Average 3"1 13| 12| 



These fish were more spotted than those in the lower pond and 

 had more red marks. The dorsal fiu had a white front edge, as in 

 young Brook-Trout 



1 Genus Brachymystax, Giintber. " Even if SaJmo fluviatUis should prove to 

 be the male of Salmo coregonoides (the type of the new genus), still the small 

 size of the ova would be a character of sufficient importance to separate these 

 fishes generically from Srihno.'' Catal. Fish. Brit. Una. vi. p. lt>3, 



