HAL.—Minnows and small chubs are found in this lake; and the flies which haunt it in summer have been aquatic larvæ in the autumn, winter, and spring; and there are usually great quantities of small shell fish, which live in the deeper parts of this water; so that char may find food even in winter; and cold, or the repose to which it leads, seems favourable to the development or conservation of fat. Most of the polar animals (the whale, moose, seal, and white bear, for instance) are loaded with this substance; and the salmon of the Arctic Ocean are remarkable for their quantity of curd: those that run up the rivers in Russia from the White Sea are said to be fatter and better, than those caught in the streams which run into the Baltic. ORN.—I agree with Physicus in his praise of the char: we are indebted to you for an excellent entertainment. HAL.—At Lintz, on the Danube, I could have given you a fish dinner of a different description, which you might have liked as a variety. The four kinds of perch, the _spiegel carpfen_, and the _siluris glanis_; all good fish, and which I am sorry we have not in England, where I doubt not they might be easily naturalized, and they would form an admirable addition to the table in inland counties. Since England has become Protestant, the cultivation of fresh water fish has been much neglected. The _burbot_, or lotte, which already exists in some of the streams tributary to the Trent, and which is a most admirable fish, might be diffused without much difficulty; and nothing could be more easy than to naturalize the _spiegel carpfen_ and _siluris_; and I see no reason why the _perca lucio perca_ and _zingel_ should not succeed in some of our clear lakes and ponds, which abound in coarse fish. The new Zoölogical Society, I hope, will attempt something of this kind; and it will be a better object than introducing birds and beast of prey—though I have no objection to any source of rational amusement or philosophical curiosity. POIET.—A fish dinner such as you have just described, combined with one such as we have enjoyed to-day, might, I think, be made an interesting experimental lecture on natural history. The analogies of the different species and genera of fishes, so distinct in the form of their organs, are likewise marked in the appearance and taste of their flesh. The salmon and the char may be regarded as the generic types of the salmo. By trout, which have sometimes red and sometimes white flesh, they are connected with the grayling and hucho. By the grayling the trout is connected with the laveret, and by the laveret the genus salmo is connected with the carp genus. The char is immediately connected with the grayling, and laveret by the umbula. By the sea trout the salmon is connected with the trout; and by the hucho, with the pike and perch families.