OUR very common "mud-minnow" (Melanura limi, Agassiz—Silliman's American Journal of Science, 1853, vol. xvi., p. 135), which is found over a wide extent of territory in America, and which, according to Dr. Albert Günther ("Catalogue of Fishes," in the British Museum, vol. vi., p. 231), is generically the same as the Umbra crameri of Europe, presents some features in its breeding habits which we have thought of particular interest, and would be greatly pleased to know if the European Umbra crameri, which Dr. Günther states inhabits the "stagnant waters of Austria and Hungary—neighborhood of Odessa," has identical habits; or, if the difference of climate, and character of the surroundings generally, have caused a more or less noticeable variation in its habits, especially during the spawning-season. We have not access to any work, on the fishes of Central Europe, that gives any details of their habits.
As we have already described it (American Naturalist, vol. iv., pp. 107, 388, Fig. 86), this little umbra is, "pure and simple," a mud-loving fish, and more strictly so than any other, unless we may except the eel (Anguilla acutirostris). During the present winter we have had unusually favorable opportunities for studying the fish during this part of the year. In December, while the weather was cool rather than cold, with but little ice, we found that hundreds of these fish were being thrown out with the mud then being scooped from the ditches of the tract of meadow on the writer's farm. On learning this, we had the mud carefully taken out by shovelfuls and examined, to learn the exact condition and position of these fish. They were, when taken from the mud, motionless, stiff, and apparently frozen; they were not brittle, and an attempt to bend or break them resulted in a very prompt but partial restoration of vitality (or consciousness?). Specimens thus roughly handled were permanently injured by being bent, even if not in excess of a degree of curvature that they can and do readily assume when in their normal condition. On placing specimens freed from mud in water of a temperature of 60° Fahr., which is pretty nearly or quite that of the ditch-water in summer, they only fully revived after lying on their sides, at the bottom of the vessel, for from twenty-five to forty minutes, and seemed to be injured permanently by the sudden change; but, if placed, with the mud still adhering to them, in water at a temperature of 40° Fahr., which became gradually warmer, by the vessel containing the fish being removed to a warm room, the minnows would become wholly themselves again, in from ten to fifteen minutes, and swim off in full vigor, as the mud slowly loosened from them and settled to the bottom of the vessel. As taken from the bottom of the ditch, the mud in which these minnows were hibernating was of about the consistency of cheese. As far as we were able to determine, these fish had burrowed tail-foremost, to a depth of from four to nine inches, and, in every instance, we believe the tail was deeper than the head, the position varying from almost horizontal to nearly or quite perpendicular.
Pursuing the investigation somewhat further, we found that, where these fishes had gone into winter-quarters in deep water, i. e., from three to five feet deep, the hibernating slumber was not as profound; and, when they were placed in clear water, at a temperature of 46° Fahr., they almost immediately swam about; slowly at first, but with steadily-increasing activity, and, in from three to five minutes, were in full possession of all their powers, and assumed the statue-like positions common to them, when seen in summer, when, for many minutes together, they will remain immovable, and only move when the near approach of an insect larva offers them a sure chance for a meal, or portion of one. It should be here mentioned that the water in the ditches from which we first gathered specimens varied from nine to fifteen inches in depth, and was coated with ice one inch thick.