The Scottish Naturalist. 



229 



their re-productive organs fully developed." Mr. Shaw, indeed, 

 reared young from these specimens, at the age of 2*4 years. 

 He adds — ; 'it is by no means improbable that portions of each 

 brood are permanent residents in fresh water, as they are never 

 observed to migrate in a dusky state, along with the shoals of 

 silvery fry. In support of such views we have the authority of 

 Dr. M'Culloch, who states that sea-trout are now permanent 

 inhabitants of a fresh water loch in the island of Lismore." 



He now marked certain young salmon-trout on their way to 

 the sea, as in the experiments subsequently performed in the 

 Tweed, the conclusions he arrived at being that the " orange" 

 or " yellow fins" became hirlings of six or seven ounces, after a 

 sojourn of about ten weeks in the sea the first season, and 

 ascend their native rivers to spawn ; and that they return the 

 next and each subsequent season as salmon-trout, with an in- 

 crease of about \y 2 lb. per annum. 



On examining the "yellow fins" of the Allan-water one natu- 

 rally places them in two series, viz., those which group them- 

 selves round the Sahno brachypo??ia of Dr Giinther, and those 

 which may be ranged under Salmo trutta. All the examples I 

 have seen are of larger size than the ordinary salmon-smolts, but 

 show quite as distinctly the loose scales of the migratory fish. 



The former, perhaps, appear to be less common than the 

 latter, but their close resemblance to salmon-smolts may have 

 prevented their capture, or else they had gone to sea earlier. 

 The examples of this form (falling under 5. brachypoma) generally 

 extend from 7 to 7^ inches in length ; and each weighs rather 

 less than two ounces. It possesses the characteristic dull bluish 

 or greenish black dorsum, so different from the aspect of a com- 

 mon or "yellow" trout, and in its migratory condition is silvery 

 throughout ; the cheeks, which possess only two or three dark 

 spots, especially appearing in strong contrast with the same parts 

 in the trout. There is a faint reddish hue on the edge of the 

 adipose fin, and a tinge of the same colour along the dorsal 

 and ventral edges of the caudal. Numerous dark spots exist 

 on the sides above the lateral line, and some in front below it ; 

 while a few very faint reddish spots occur on the sides, occa- 

 sionally visible only on one side. The pectoral fins are pale 

 lemon, with a little black pigment towards the tip. The ven- 

 tral and anal are quite pale. The tail has a blackish border 



