296 THE ZOOLOGIST. 



glided over the sand, glistened on the stones, or fringed the 

 green branches with their multitudes ; whilst the Conferva 

 afforded lurking places for Water- beetles, Cyprides, Leeches, 

 Worms and other invertebrates which preyed on the more 

 minute infusoria, diatoms, and desmids. From the platform on 

 the southern side, indeed, the sight of all this natural beauty 

 and luxuriance, as well as the shoals of sportive fishes, in- 

 voluntarily recalled the coral reefs of the South Pacific, with 

 their gaily tinted polyps and the brightly coloured fishes which 

 frequented them. 



Since the foregoing period a new rearing-ground has been 

 made and trees planted by the border ; and it is a noteworthy 

 feature that the young fishes thrive best in the pond fringed by 

 the young trees — apparently since insect-life has thus been 

 materially increased. 



At the end of the second year most become Smolts, assume 

 the silvery dress and migrate to the sea, apparently passing at 

 once to deep water, for very few small examples (7 in.) have 

 been captured. 



It is in the sea that the Salmon obtains the abundant and 

 rich nourishment (Herrings, Sand Eels, &c.) which enables 

 it to increase rapidly in length and weight ; so that next year 

 it returns to its native river as a Grilse of 2-5 or more pounds ; 

 or if it remains a year longer it enters the river as a small 

 Salmon in spring. Similar results were obtained by marking 

 Kelts, or spent fishes, the short and the long sojourns in the 

 sea in Scotland being respectively five months and fifteen and 

 three-quarter months. 



Its food in the sea was long a source of dubiety. Thus Knox, 

 Huxley, Queckett and others thought that it fed on the eggs of 

 various kinds of Echinodermata, small Crustacea, and Sand 

 Eels, apparently linking on the colour of the food with that of 

 the muscle of the Salmon. 



The Salmon is a type of a fish having demersal eggs — that 

 is, they are deposited on the bottom ; and in such fishes the 

 eggs, while they are far larger in size, are less numerous than 

 in those having floating or pelagic eggs. Thus the Salmon has 

 about 28,000 eggs, the Cod from three to nine millions. The 

 young of the Salmon is not only much larger than in the case 



