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CAUSES OF VARIETY IN TROUT. 223

twentieth fish I have taken in an hour, and it is a grayling of at least fifteen inches long; and there is a trout of eighteen, and several salmon trout, which look as if they had run from the sea.

HAL.-These salmon trout have run from a sea, but not from a salt sea; they are fish of the Traun See, as it is called by the Germans, or Traun Lake, which is emptied by this river.

PHYS.-Tell us why they are so different from the river trout, or why there should be two species or varieties in the same water.

HAL.-Your question is a difficult one, and it has already been referred to in a former conversation; but I shall repeat what I stated before,-that qualities occasioned by food, peculiarities of water, &c. are transmitted to the offspring, and produce varieties which retain their characters as long as they are exposed to the same circumstances, and only slowly lose them. Plenty of good food gives a silvery colour and round form to fish, and the offspring retain these characters. Feeding on shell-fish thickens the

stomach, and in many generations, probably, the gillaroo trout becomes so distinct a variety, as to render it doubtful if it be not a distinct species. Even these smallest salmon trout have green backs, only black spots, and silvery bellies; from which it is evident that they are the offspring of lake trout, or lachs forelle, as it is called by the Germans; whilst the river trout, even when 4 or 5lbs. as we see in one of these fish, though in excellent season, have red spots. -But why that exclamation?

POIET.-What an immense fish! There

he is!

HAL.-I see nothing.

POIET.-At the edge of the pool below the fall, I saw a fish, at least two or three feet long, rising with great violence in the water, as if in the pursuit of small fish; and. at the same time I saw two or three minnows or bleaks jump out of the water. What fish is it?-a trout? It appeared to me too long and too slender for a trout, and had more the character of a pike;-yet it followed, and did not, like a pike, make a single dart.

HAL.-I see him: it is neither a pike nor à trout, but a fish which I have been some time hoping and expecting to see here, below the fall-a salmo hucho, or huchen. I am delighted that you have an opportunity of seeing this curious fish, and of observing his habits. I hope we shall catch him.

POIET. Catch him! we have no tackle strong enough.

HAL.--I am surprised to hear a salmon fisher talk so: yet he is too large to take a fly, and must be trolled for. We must spin a bleak for him, or small fish, as we do for the trout of the Thames or the salmon of the Tay. Ornither, you understand the arrangement of this kind of tackle-look out in my book the strongest set of spinning hooks you can find, and supply them with a bleak; and whilst I am changing the reel I will give you all the information (which, I am sorry to say, is not much) that I have been able to collect respecting this fish from my own observation or the experience of others. The hucho is the most predatory fish of the salmo genus, and is made like an

ill-fed trout, but longer and thicker. He has larger teeth, more spines in the pectoral fin, a thicker skin, a silvery belly, and dark spots only on the back and sides-I have never seen any on the fins. The ratio of his length to his girth is as 8 to 18, or, in well-fed fish, as 9 to 20; and a fish, 18 inches long by 8 in girth, weighed 16215 grains. Of the spines in the fins, the anal has 9, the caudal 20, the ventral 9, the dorsal 12, the pectoral 17: having numbered the spines in many, I give this as correct. The fleshy fin belonging to the genus is, I think, larger in this species than in any I have seen. Block, in his work on fishes, states that there are black spots on all the fins, with the exception of the anal, as a character of this fish: and Professor Wayner informs me he has seen huchos with this peculiarity; but, as I said before, I never saw any fish with spotted fins-yet I have examined those of the Danube, Save, Drave, Mur, and Izar: perhaps this is peculiar to some stream in Bavaria-yet the huchos in the collection at Munich have it

not. The hucho is found in most rivers tributary to the Danube-in the Save and Laybach rivers always; yet the general opinion is, that they run from the Danube twice a year, in spring and autumn. I can answer for their migration in spring, having caught several in April, in streams connected with the Save and Laybach rivers, which had evidently come from the still dead water into the clear running streams, for they had the winter leech, or louse of the trout, upon them: and I have seen them of all sizes, in April, in the market at Laybach-from two feet long to six inches. It is the opinion of some naturalists, that it is only a fresh water fish; yet this I doubt, because it is never found beyond certain falls-as in the Traun, the Drave, and the Save; and, there can be no doubt, comes into these rivers from the Danube; and probably, in its largest state, is a fish of the Black Sea. Yet it can winter in fresh water; and probably many fish never return to the Black Sea, but fall back into the warmer waters of the great rivers, from which they migrate in spring,

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