186 SALMONID^ OP BRITAIN. 



In streams where, due to some local cause,* the trout are small, it is not 

 uncommon to perceive the par bands, as well as the black and red ocellated spots 

 retained throughout life.f I found this obtained among some from brooks near 

 Penzance, similarly so in Scotch burns and Welsh mountain streams: in fact, they 

 were as brilliant as young salmon pars, to which their colours bore a striking 

 resemblance. Although we must anticipate estuary and fresh-water trout to be 

 more vividly coloured than are those leading a more strictly marine life, still 

 among the former the numerous variations in tints and markings have been 

 explained in more than one manner, as the nuptial season, the effects of temporary 

 emotions, of age, or the state of the fish's health, or its food. 



Clear water in rapid rivers or lakes, especially when the bottom is pebbly, is 

 seen to contain somewhat silvery fishes, with black X-shaped spots. Sir William 

 Jardine remarked that a variety very frequent among trout in small Alpine lochs 

 in Scotland had large dark or red spots placed in a pale or clear surrounding field, 

 these marks being very large, while the principal part of the spotting was 

 confined to the centre of the body. I have likewise obtained this form of coloured 

 trout from deep holes in the course of burns, but the spots have been present all 

 over the fish, while they have also been recorded from Wales. 



The colour, depth, temperature, and character of the water also have an 

 influence on the fish, the presence of moss and peat, or a muddy bottom, causing 

 a dark tint to be assumed, while some captured in dark holes or caves have been 

 seen nearly black. 



The coloui's of the Sahnones may be shortly summed up as silvery, with or 

 without black spots]: among the marine, and some resident in large clear pieces of 

 water, as lochs or rivers : more or less speckled with black and red when non- 

 migratory and living in fresh Avaters : while, should the race be small, a persistence 

 of the transverse bars or bands on the body, which are j^resent in most of the 

 young, may be observed even in adults. Irrespective of changes in colour 

 externally, a difference of food may occasion it in the flesh of these fishes, whether 

 the alteration in diet is due to choice or to necessity. Thus Crustacea and their 

 allies, which appear to colour it red or pink, may be absent from the locality these 

 fish frequent, or if present they may not relish that food so much as some other 

 which exists in the water. In certain rivers there are trout with white and others 

 with red flesh, the two forms being in good health and equally delicate for the 

 table. This has also been observed in the American char, Salmo fontinalis, 

 introduced into this country, and in which it has been clearly traceable to the 

 food upon which it subsists. 



In some races of our fresh-water trout the males have been said to develop 

 at the breeding season a knob or hook at the upper end of the lower jaw, while 

 other forms have been erroneously stated to be deficient in it. This sexual 

 development, however, is seen in all races of our fresh-water trout, provided the 

 specimens are permitted to live to a sufiicient age, while in some well-fed examples 

 as in Lochlevens at Howietoun, I have observed it at the third season. There is 

 in its mode of development but little difference from what takes place in the 



* Percy St. John (in Wild Sjmrts of the West, p. 240) remarked that he "never observed the 

 effect of bottom soil upon the quality of fish so strongly marked as in the trout taken in a small 

 lake in the county of Monaghan. The water is a long irregular sheet, of no great depth, one 

 shore bounded by a bog, the other by a dry and gravelly surface. On the bog side the trout are 

 of the dark and shapeless species peculiar to moory loughs, while the other affords the beautiful 

 and sprightly variety, generally inhabiting rapid and sandy streams. Narrow as the lake is, the 

 fish appear to confine themselves to their respective limits : the red trout being never found upon 

 the bog moiety of the lake, nor the black where the under surface is hard gravel." 



t Mr. Harvie-Brown has informed me of a dwarf trout said to exist in loch Mulach Corrie 

 in Sutherlandshire which appears to be "a small but apparently adult form about the size 

 of a big minnow and very rarely got. It may be the young of the so-called gillaroo, but if so it 

 is a curious departure as it is utterly without par bands." 



J We must not forget that brook trout vary greatly in colour even when in the same locality ; 

 thus Ephemera in 1853 remarked of those in the Wandle that such as " feed under the cover of 

 the trees, or lie perdus under banks or artificial ' hides ' during sunshine, are dark brown and 

 yellow; those that frequent the unshaded streams with a clear sandy bottom are of a silvery 

 hue" (p. 274). 



