If, as many suppose, the earliest fish are those which have soonest spawned during the preceding autumn, and have since descended towards and recovered in the sea,—­then a precocious spawning would necessarily lead to the speediest supply of clean fish in mid-winter; but the fact referred to has not been ascertained, and it may therefore still be as reasonably alleged that the winter fish (an opinion supported by the fact of their unusually large size) have continued in the sea since spring.  At least a majority of them, (for they differ somewhat in their aspect and condition,) instead of having spawned soonest in autumn, have probably rather spawned last of all during the preceding spring, and so required for their recovery a corresponding retardation of their sojourn in the sea.  The reasons why grilse seldom show themselves till the summer is well advanced, are very obvious, now that we have become conversant with their true history.  They were only smolts in the immediately preceding spring, and are becoming grilse from week to week, and of various sizes, according to the length of their continuance in the sea.  But they require at least a couple of months to intervene between their departure from the rivers in April or May, and their return thither;—­which return consequently commences, though sparingly, in June, and preponderates in July and August.

But we are making slow progress with our intended exposition of Mr Scrope’s beautiful and instructive volume.  Although salmon and salmon streams form the subject and “main region of his song,” he yet touches truthfully, albeit with brevity, upon the kindred nature of sea-trout, which are of two species—­the salmon-trout and the bull-trout.  The fry of the former, called orange fins, (which, like the genuine parr, remain two continuous years in the river,) greatly resemble the young of the common fresh-water trout.  “Like the grilse, it returns to the river the summer of its spring migration, weighing about a pound and a half upon an average.”—­P. 63.  We think our author rather over-estimates their weight at this early period.  Herlings (for so they are also named on their first ascent from the sea) rarely weigh one pound, unless they remain for a longer time than usual in salt water.  In this state they bear the same relation to adult sea-trout as grilse do to salmon, and they spawn while herlings.  They afterwards increase about a pound and a half annually, and in the summer of their sixth year (from the ovum) have been found to weigh six pounds.[16] Whether this is their ordinary ultimate term of increase, or whether, having every year to pass up and down the dangerous, because clear and shallow waters, exposed to many mischances, and, it may be, the “imminent deadly breach” of the cruive-dyke, and thus perish in their prime, we cannot say:  but this we know, that they are rarely ever met with above the weight of six or seven pounds.

[Footnote 16:  See Mr Shaw’s paper “On the Growth and Migration of the Sea-trout of the Solway.”—­Transactions of the Royal Society of Edinburgh.  Vol.  XV.  Part iii. p. 369.]