Mr. Yarrell writes as follows-"That the salmon is a voracious feeder may be safely inferred from the degree of perfection in the arrangement of the teeth, and from its known habits, as well as from the well-known habits of the species most closely allied to it; yet of the many observers who have examined the stomach of the salmon to ascertain the exact nature of that food which must constitute their principal support, few have been able to satisfy themselves."* Faber says that "the common salmon feeds on small fishes, and various small marine animals." Dr. Fleming, as quoted by Yarrell, remarks that their favourite food in the sea is the sand eel, and Yarrell says he has himself taken the remains of sandlaunce from the stomach. That herrings enter largely into the list of the food of the salmon while in the sea, I can state from personal observation. The salmon in whose stomachs I frequently found one, two, three, or even four herrings together, were from the coast of Norway. Some of the herrings were nine or ten inches long. I never found any other fish in their stomachs, nor, indeed, any other kind of food. This, however, will do no more than prove that salmon feed greedily enough on herrings, and not that other fish do not form part of their diet. There is an abundance of herrings off the coast of Norway, and probably they were more readily captured by the salmon than other fish, during the months of May, June, and July, at which time I made my examinations. With respect to the river or fresh-water salmon, I never detected the smallest trace of food of any sort either in the stomach or intestines; and Mr. Bowring, a most respectable fishmonger at Wellington, obligingly examined for me a great number of stomachs. We neither of us ever found any food in them, nothing but a thick white or yellow mucus with the gritty particles already noticed, and some intestinal worms, amongst which tape-worms were the most common. But it is asserted by many that the idea of a salmon abstaining from food the whole time the fish is an occupant of fresh water, is a physiological heresy; that so active a fish must eat in order to maintain itself and supply muscular force; and that the very fact that salmon are taken with minnow, worm, or fly, is a convincing proof that they do feed in fresh water; that the vacuous condition of the stomach is readily accounted for by the well-known habit this fish has, in common with many others, of emptying its stomach when hooked or netted, by an instinctive act of fear, or to facilitate its escape by lightening its load. That the salmon does occasionally throw up the contents of its stomach is probable enough, and has indeed been witnessed. "I was * See "British Fishes," ii. p. 52. on the sea in a boat," writes Mr. Campbell, "rowing, one bright, calm day, along some rocks near the mouth of a salmon river, when I espied one of the poaching nets used by the Highlanders. . . . . We went towards the net, and in so doing started a salmon, which dashed into it. I saw the salmon strike and entangle itself, and in a moment begin to vomit a number of herring-fry. I could see them quite distinctly, for we were exactly over the fish. I pulled up the net as fast as I could, and in a second the salmon was in the boat. So quick was I, that there were upwards of a dozen of the fry still in his mouth, although he had been ejecting a shower of them as I drew him to the surface. Of course there was nothing in his stomach; but the idea of saying that salmon do not eat is ridiculous. I have myself caught scores with a worm, and thousands are so taken every year, which sufficiently proves that they eat; but when they find themselves fast on a hook or in a net, they disgorge, like the Solan goose, or as the salmon did that I have just described, and thus nothing is found in their stomachs when they are opened."* Another way of accounting for the absence of food in the salmon's stomach is by its extraordinary digestive properties. "The rapid growth of the fish seems to imply that its digestion must be rapid, and may perhaps account for there never being food in its stomach when found."+ Let us examine these various arguments. 1. The salmon vomits up his food when hooked or netted, consequently he has nothing in his stomach. Granted that he does sometimes, does it follow that he always does so? Or if he always did so, can he vomit up the indigestible portions from the intestines? For it must be remembered that the whole intestinal tract in river-salmon, as a rule, never shows evidence of food. But since herrings and other fish are frequently found in the stomachs of sea-salmon, it is evident that the vomiting theory must fall to the ground. If they invariably eject the food from their stomachs in fresh water, why do they not invariably do so in salt? 2. The rapid digestion will account for the absence of food in the stomach. But if river-salmon feed, as asserted, there must be times at which the fish is caught immediately after having swallowed some food; for though the digestion may be rapid, it cannot be instantaneous. Besides, the digestion theory will not account for the absence of all indications of food in the intestine. 3. The fact that salmon are frequently taken with a worm, minnow, or fly, is a proof that the fish do feed whilst in the Life in Normandy," pp. 36 and 37. Ed. 1865. "Harvest of the Sea," p. 192. fresh water. I do not pretend to say that a fresh-water salmon never by any chance takes a particle of food, but that its doing so is so rare as merely to prove by its exception the generality of the rule. It must also be remembered that some fish will occasionally take a tempting bait more for sport than for food. A pike, when absolutely gorged with food, will not unfrequently seize a bait in his mouth, and yet refuse to swallow it, as trollers who use a gorge-bait well know. What does an artificial salmon-fly resemble in nature? Certainly no kind of winged insect, not even a gaudy libellula or agrion either in form or motion, for no libellula ever swims in the water, least of all after the fashion in which the artificial fly is made to locomote by the angler. Some have thought, among whom is Sir Humphrey Davy, "that the rising of salmon and sea-trout at these bright flies, as soon as they come from the sea into rivers might depend upon a sort of imperfect memory of their early smolt habits." But it is more probable the salmon takes the glittering fly-which is allowed to sink a little in the water for a fish, for fish forms his principal food when an inhabitant of the sea. But be this as it may, the undoubted fact that the stomachs and intestines of fresh-water salmon are almost invariably found empty is a convincing proof, for reasons adduced above, that this fish abstains from food during its sojourn in fresh water. 4. With respect to the physiological paradox as to how an animal can live without taking food, it must be borne in mind in the first place, that, notwithstanding the voracity of the carnivorous fishes, and their extraordinary digestive capabilities, they are able to exist for long periods of time without food. Gold and silver fish may be kept for months without perceptible food, and certainly as we descend the scale of creation we shall find instances of long-continued abstinence more frequently. Snails in conchological cabinets have been known to live for years without a particle of food or drink. Frogs and toads will unquestionably exist for years immured in wood and stone in positions which entirely forbid the introduction of any kind of food. But there must be a limit to this power of existing without food. A salmon, if he was never to eat, would undoubtedly die. But how, it will be asked, can muscular force be maintained for so many months without food? There can be no other explanation than this, that the salmon lives on his own abundant fat, stores of which are laid up throughout the whole body of the fish, but especially in the abdominal regions. This supply of fat was deposited during the time the salmon was an inhabitant of the sea, and when, as I have said above, he is a voracious feeder. Now we know, notwithstanding the assertion of old Izaak Walton* to the contrary, that the longer a salmon continues in fresh water the more does his flesh deteriorate. Mr. Alexander Russel, a good authority on salmon, is quite right when he says that "salmon taken in or near the sea are the best for food." Let any one compare the difference in the quality of the flesh between a sea-salmon and one that has long been a sojourner in fresh water. He I will notice in the sea-salmon the abdomen to be soft and tremulous with abundance of fat, that of the river-fish firm and comparatively destitute of fat. And this continued abstinence from food is, no doubt, in some measure the reason of the fish's gradual deterioration till the exhausting process of spawning renders the salmon now altogether unfit for food. The salmon's abode, therefore, in fresh water should be regarded as a quasi-hybernation, during which life is maintained upon stores already laid up in the organism. That muscular force may be maintained, and in fact that it is chiefly kept up by the combustion, not of the nitrogenous elements, but of the carbonaceous, has been rendered tolerably certain, and the circumstance that a salmon may move about for a long time in fresh water without supplies of food beyond his own abundant fat, is not actually much more than a further instance of what takes place in hybernating animals, as the bear, which goes fat into winter quarters and comes out very thin. The same may be said with regard to experiments that have been made, showing that the Swiss mountains may be ascended solely upon the strength afforded by butter and other nonnitrogenous food. According to the researches of Dr. John Davy, "the gastric juice, and probably the other fluids concerned in the function of digestion in fishes, are not secreted till the secreting organs are stimulated by the presence of food-a conclusion in harmony with a pretty general physiological law, and in accordance with what has been best ascertained respecting the gastric juice in other animals." Dr. Davy infers the following corollary from the above, "that the migratory species of salmon, such as the salmon and sea-trout, which attain their growth, and become in high condition in the sea, there abundantly feeding and accumulating adipose matter, though not always abstaining in fresh water, which they enter chiefly for the purpose of breeding, are at least capable of long abstinence there without materially suffering." He suggests the probability of this being owing to none of their secretions or *Walton's words are:-"It is observed that the further they get from the sea, they be both fatter and better." "Physiological Researches," p. 168. excretions, with the exception of the milt of the male and the roe of the female being of an exhausting kind. The conclusion, then, at which I think we may safely arrive with regard to the food of the salmon is-that it feeds freely in the sea, and chiefly on other kinds of fish, such as sandlaunces, herrings, and other clupeidae, though other animals, such as shrimps, and various crustacea occasionally form part of its diet; that during its sojourn in the sea the salmon lays up a store of adipose matter; that it very seldom feeds during its abode in the fresh-water rivers, but lives on the supplies of its own internal fat; that though for some time the flesh does not perceptibly deteriorate, it is rendered poorer in quality towards the end of its sojourn in the fresh water, both from the exhaustion of its own supplies of fat and from the effects of spawning; that it rapidly improves when it has reached the salt water, when it again lays up a fresh supply of adipose matter, which will support it during its sojourn in the rivers. A SYNOPSIS OF THE RECENT BRITISH OSTRACODA. BY GEORGE STEWARDSON BRADY, M.R.C.S., C.M.Z.S., Secretary to the Tyneside Naturalist's Field Club. Or the various orders included in the great tribe Entomostraca, there is, perhaps, not one more generally interesting than that of which we propose to treat in the present paper. When we consider the great abundance and wide dispersion of the Ostracoda through the fresh waters and seas of our own period, and the countless myriads in which the shells of antediluvian species have come down to us, embedded in strata of varied character and age-for example, Silurian, Liassic, Carboniferous, Permian, Tertiary, and Post-tertiary-it will be evident that the geologist and palæontologist must, to a very large extent, share their interest in this group with the student of recent zoology and physiology. It will be seen also that any light which may be thrown upon the structure and habits of living forms must likewise be of great importance to the student of extinct species, as tending to exhibit more clearly their natural affinities, and to establish sounder principles of classification than can be attained by the study merely of the external covering of the animal, which only is left to us in the case of fossil examples. The prodigious numbers in which the fossilized carapaces of these creatures sometimes occur, is |