SALMO FARIO, VAR. AUSONII. 293 



colours. The black colour is common in waters that contain iron, as well as 

 in woods, but even then when the water is shallow, and. light penetrates 

 through the foliage, the fishes grow pale. 



The size of the Trout does not usually exceed one foot, and the weight is 

 half a pound to a pound, though Lloyd believes that he killed it in Sweden of 

 eleven pounds' weight, and Heckel and Kner mention a fish taken in 1851 at 

 Wiener Neustadt, which was thirty -five inches long, nine inches high, and 

 weighed twenty-two pounds. It is not rare for Trout to attain a weight of 

 fifteen to seventeen or twenty pounds in localities in which suitable food is 

 abundant; and Valenciennes refers to Trout of three to four feet in length, 

 though the largest specimen taken recently in France appears to have weighed 

 twelve kilogrammes. 



In the young fish the size of the eye, relative length of the head, and 

 other proportions are generally less; but the young are also distinguished 

 by transverse bands, termed Parr markings, of dark-brown, like those of the 

 Perch, which gradually vanish with age. The young fish has also a deeply- 

 forked caudal fin, while in old age the tail becomes rounded. The males 

 are characterised by a larger head, fewer and stronger teeth on all the bones 

 of the mouth, as well as by the hooked mandible. 



Trout flourish best in clear cold running water, and when found in lakes 

 are most numerous at the mouths of streams which flow from them. They 

 swim with remarkable speed, but lie still for a long time in deep pools, or 

 in the shadow of overhanging bushes and trees. Like the Salmon, they 

 often make sudden leaps out of the water, and pass over weirs, small water- 

 falls, and other impediments. They live on insects, molluscs, spawn, worms, 

 and small fishes, and rush impetuously after gnats, which skim over the 

 surface of the water. When their weight is about two pounds they are as 

 greedy as Pike. 



They spawn in the autumn, from October to December ; and in North 

 Germany, Benecke records spawning as late as January ; but this is probably 

 in the mountain districts. The female is mature at a length of eight inches. 

 The urogenital papilla is then enlarged and tumid, and in both sexes there is a 

 thickening of the skin, and, according to Benecke, a swelling of the fins. The 

 eggs in a two-year-old Trout number two hundred to five hundred ; in the 

 third year the number increases from five hundred to one thousand ; in the 

 fourth to the fifth year the number is two thousand. They are four to five 

 millimetres in diameter, yellowish or reddish, and are laid in small quantities, 

 at intervals of many days, being placed between stones, under trunks of trees, 

 but also in holes, not unlike nests, which the fishes excavate. The spawn when 

 deposited is partially covered with gravel. The period of incubation, according 



