This fish is forced front the sea by a parasitical in sect, adhering to every part of his body, and which fishermen call the sea-louse. It is neither the oniscus asilus, nor monoculus Jziscinus of Linnxus; nor has it yet, so far as we know, been described by any naturalist. It dies and drops off, after the salmon has been but for a very short time in the fresh water. In this condition, and at this period, they are in the highest perfection ; their form is elegant, their colour beautiful, their flesh comes off in flakes, and is firm, red, and delicious. Af ter this insect leaves them, and while the fresh water becomes their temporary element, they daily decline, in co_our, in health, and in vigour; and when shottcn or 'Celts,* they wou:d hardly be known to be the same species of fish which we saw when in a clean state. Their heads look large, they are lank, lean, flabby ; and the fine silvery cast in which they left the sea, is turned into a dirty reddish brown; the rays of their fins are jagged and torn ; their scales are almost rubbed off ; and worms (lernea sahnonea) infest their gills. In the lower jaw of the male, a strong gristly protuberance is observable ; it somewhat resembles the beak of birds of the order accipitres, and produces a hole in the upper jaw, and through which it has sometimes been known to perforate. This curvature is said to leave them whenever they get to the sea, for which in this situation they set out, occasionally stopping in still water, as their weakness at this time requires rest, even to enable them to go down the stream.
In all the tribe of migratory animals, whether of the air or of the water, few or none exhibit a more wonder ful instinct than that of the salmon.
Scarcely have they enjoyed the light of the sun, when, without a guide to pilot, or a parent to protect them, they undertake a journey, often of some hundred miles, to visit an element with which they are totally unac quainted. They remain in the sea but for a short time, then return, and through toils and dangers, ascend the very streams which they descended, in order to spawn on the spot which gave them birth. Those bred in the Linth, are known to take their course up the Rhine, from that river into the Aar, then through the lake of Zurich, and so again into their native stream. They effect their passage up the Thames, a considerable way above London, although annoyed by the keels and ca bles of various craft, the continual plying of oars, and all the filth and garbage of that overgrown metropolis. In like manner, over cascades, through many windings, rapid rivers, and extensive lakes, they push up to the very interior parts of North America, in order to breed in their natal waters. This is an instinct beyond the power of naturalists to explain; indeed it is but little, with all their boasted knowledge, that they can reach, " in nature's infinite book of secrecy." There are, however, some instances of animals mistaking their in stinct. The flesh-flv has been seen to deposit its eggs
in the flower of the fetid stapelia, being deceived by the resemblance of its smell to that of carrion. So have we known salmon run up rivers in which they were not bred; however, this is a circumstance wi:ich rarely happens.
Salmon delight in rivers which have Alpine sources.
They prefer to all others a gravelly pebbled bottom, where there are large stones, clear of every kind of slime. They avoid waters, or streams flowing upon inundic ore, or that arc impregnated with calcareous, or selenetic particles. They are impatient of shade, unless in the very heat of summer, and dislike to remain for any length of time in such parts of rivers where the banks are wooded, or near hanging rocks, that exclude the sun from the stream or pool. They are extremely sensible of approaching changes in the weather; they then leap above the water, and apparently enjoy the prospect of coming rains, and showery winds. Imme diately before and in the time of thunder, they keep close to the bottom, and are seemingly affected with every concussion in the air. They always lie with their heads pointing up the river, and seldom or never swim down the stream, unless on their journeying to the sea, when disturbed by the bawling or shooting of nets, the prowling of the otter, or when exhausted by the fatiguing tackle of the angler.
To the admirers of nature, no sight can be more gra tifying than to observe salmon ascending torrents, and vaulting over rocks of such a height as no other fish would attempt. We have heard much said, and seen much written, both in prose and in verse, of the Ken nerth, a salmon leap, upon the river Tivy, in Pembroke shire. Drayton, with some other poets and authors, in describing this place have mentioned, that the salmon takes his tail in his teeth in making the spring to leap. This assertion has been long, and continues still a vul gar error. There is, however, a more remarkable fall than this, called the Keith, upon the river Erich, in the county of Perth. That rock is about thirteen feet high, and the whole river, which is a very considerable one, bursts through a cleft of only a few feet in breadth. From a long continuance of dry weather, and conse quently when there is little water in the river, these fish lie in the pools and holes immediately below this cascade." It is at that time an amusing sight to sur vey them from the banks above, all regularly disposed, tire above tire, resting upon their fins, and waiting with anxious and eager expectation for a coming flood, to assist them in their passage upwards. When this hap pens, they then all prepare to take the leap. In their first efforts they sometimes fail, and tumble down stu pified; but undismayed, and with an unremitting ar dour, they renew their attempts, until they prevail in gaining the summit of this fearful gap.