character of the cuttle-bone in Sepia, and of the horny pen which takes its place in the various calamaries, and notes the lack of any similar structure in Octopus. He dissects in both sexes the reproductive organs, noting without exception all their essential and complicated parts; and he had figured these in his lost volume of anatomical diagrams. He describes the various kinds of eggs, and, with still more surprising knowledge, shows us the little embryo cuttle-fish, with its great yolk-sac attached, in apparent contrast to the chick's, to the little creature's developing head. But there is one other remarkable feature that he knew ages before it was rediscovered, almost in our own time. In certain male cuttle-fishes, in the breeding season, one of the arms develops in a curious fashion into a long coiled whip-lash, and in the act of breeding may then be transferred to the mantle-cavity of the female. Cuvier himself knew nothing of the nature or the function of this separated arm, and indeed, if I am not mistaken, it was he who mistook it for a parasitic worm. But Aristotle tells us of its use and its temporary development, and of its structure in detail, and his description tallies closely with the accounts of the most recent writers. A scarcely less minute account follows of the 'Malacostraca' or crustaceans, the lobsters and the crabs, the shrimps and the prawns, and others of their kind, a chapter to which Cuvier devoted a celebrated essay. There be many kinds of crabs--the common kind, the big 'granny' crabs, the little horsemen-crabs, that scamper over the sand and which are for the most part empty, that is to say, whose respiratory cavities are exceptionally large; and there are the freshwater crabs. There are the little shrimps and the big hump-backed fellows, or prawns; there are the 'crangons' or squillae; and the big lobsters and the crawfish or 'langoustes', their spiny cousins. We read about their beady eyes, which turn every way; about their big rough antennae and the smaller, smoother pair between; the great teeth, or mandibles; the carapace with its projecting rostrum, the jointed abdomen with the tail-fins at the end, and the little flaps below on which the female drops her spawn. In more or less detail these things are severally described, and the many limbs severally enumerated, in one kind after another. The descriptions of the lobster and the langouste are particularly minute, and the comparison or contrast between the two is drawn with elaborate precision. In the former, besides other differences between male and female, the female is said to have the 'first foot' (or leg) bifurcate, while in the male it is undivided. It seems a trifling matter, but it is true; it is so small a point that I searched long before at last I found mention made of it in a German monograph. The puzzling thing is that it is (as we should say) the last and not the first leg which is so