144 SALMONID^ OF BEITAIN. 



non-migratory forms are in two main primary divisions of colour, as some loch 

 trout are possibly anadromons forms wMch have become land-locked (see pp. 5, 

 104, 105), and their tints are mainly silvery during the smolt stage, and subse- 

 quently golden and spotted, possibly this silvery colour may sometimes be 

 sj-mptomatic of sterility. Thus the Lochleven is normally of a silvery colour, with 

 dark fins between its third and fourth seasons, subsequently nearly resembling 

 the brook trout, into which form it may degenerate : it is a somewhat delicately 

 shaped but rapidly growing race, with rather weak maxillae. While the estuary, 

 lake, river and brook trout are all golden, with purplish reflections and more 

 or less covered with black and vermilion spots. 



CommencLQg with examining the subject of variation in colours, we find that 

 the adult salmon and sea trout, when in their prime, have a beautiful silvery 

 sheen, which is more or less rapidly lost when absent from the sea. This may, 

 in fact, be taken as the normal colour of the Salmones when in their highest 

 condition. Should salmon be reared in fresh water, and the smolts debarred from 

 going to the sea, the upper two-thirds of the body and the dorsal fin become 

 densely covered with black spots (see plate iii, fig. 3), while sometimes a white 

 edging shows itself on the front margin of the dorsal and anal fins. Likewise, 

 as already observed, the land-locked forms of Lake Wenern are spotted more like 

 sea trout than salmon, and in some par bands are persistent through life (see 

 p. G ante). Thus, it would appear that a fresh- water residence increases 

 the amount of colour, while the silvery sheen is less highly developed. Here we 

 see a connecting link in colour between the anadromous forms and the young 

 brook or lake trout, with increased colours consequent upon a fresh-water 

 residence. 



A very instructive instance is recorded by Mr. Nichols in his Acclimati- 

 sation of the Salmonidce at the Antipodes : Its History and Results, 1882, wherein 

 he tells us how the eggs and milt of a race (it is not recorded which) of British 

 sea trout were transmitted to Tasmania, and one of the progeny 18 in. long was 

 received in the National Collection in 1874. Externally, its form is similar to our 

 northern race Salmo trutta, but it only possesses 36 csecal appendages, numbers 

 more symptomatic of our southern race of sea trout, the sewin or 8. camhricus. 

 The difiiculty was met by suggesting the fish to be a hybrid, but as sea trout 

 solely were spawned it could only have been so between our two anadromous races. 

 These salmon-trout eggs arrived in Tasmania, May 5th, 1886, were placed in the 

 breeding-ponds, and from them 900 fry were reared. A number of these fry were 

 put into a specially constructed pond, fed by a small rill of bright cool water, 

 where they were disturbed as little as possible. By the middle of October, 1867, 

 many of these par had put on the smolt dress, when doubtless feeling the migratory 

 impulse, they leaped upon the bank and perished in numbers. In July, 1869, four 

 pairs spawned in the ponds.* It is thus clear that this fish with anadromous 

 instincts was raised from the eggs transmitted from England, and distinctly 

 demonstrates that the number of cseca are subject to variations, consequently they 

 are almost useless as a definite guide to species. Here some change in climate or 

 food had induced such a marked difference, that in the Antipodes two forms of 

 sea trout might be detected in one specimen. 



In the National Collection may be seen specimens of what are termed in the 

 Catalogue "hybrids between Sewin (8. cambricus) and River- Trout (8. fario) " 

 received from Wales through Mr. Peel and Mr. Morgan. Their colours and 

 general appearance, as will be more particularly referred to when describing the 

 sewin, show a graduated seriesf from the a.nadromous sea into the fresh-water 

 forms. Similar series likewise exist in that collection which are located as 

 " specimens supposed to be hybrids between Salmo trutta and Salmo gaimardi " 

 or sea and brook trout, and others likewise asserted (but without any corroborative 

 evidence) to be hybrids between the so-called Galway sea trout, 8. gallivensis, and 

 the brook trout, one form merging into the other. Also I shall allude to a series 



* This disposes of the negative evidence of sea trout becoming sterile if retained in a fresh- 

 water pond without being able to descend to the sea. 



•f This series is considered by Dr. Gunther to show the effects of hybridization I 



