most interesting objects of study to the general zoologist, they are at least not unimportant to man and his surroundings. Minute Nematodes abound in moist soil around the roots of plants, &c. In animal parasites we have the round worm, Ascaris lumbricoides, which inhabits the alimentary canal of man; A. mystax, found in the cat and dog, and A. megalocephala in the horse and ox. Parasitic in plants, they cause the formation of galls and other pathological growths; while the "Vinegar Eel," Anguillula aceti, "which occurs so often in weak vinegar, is another familiar example of this group." No fewer than "twenty-two species have been described as parasitic in man," and hence the cui bono which has often irritated so many amiable naturalists can scarcely be applied with effect to the specialist who investigates the life-histories of these unbidden guests.
Rotifers are under the charge of Mr. Marcus Hartog. These microscopic animals always recall to the mind of the writer that, in conjunction with Hudson, his old correspondent, P.H. Gosse, so aptly designated by Charles Kingsley as "that most pious and most learned naturalist," passed the last years of a long zoological vigil in their Monograph. Gosse was undoubtedly a true zoologist, but there is a danger lest he be principally remembered as the author of that bizarre publication 'Omphalos.' Mr. Hartog bears witness to the value of the 'Monograph,' and may be said to supplement it by giving the true biological details of the group. It is surprising how many interesting details may be studied in the life-histories of Rotifers. "Almost any organic infusions freely exposed to the open air will yield Ploima shortly after the active putrefaction is completed. The finer water weeds yield most of the beautiful tubicolous forms. A whole group of species and genera are quasi-pelagic in fresh and salt water, constituting a large proportion of the 'plankton' or floating life near the surface; and some of them are found in deep water, or in the depths of the lakes." Others again are parasitic.
Mr. W. Blaxland Benham has contributed a very useful treatise on the Polychaet worms. Most marine anglers are acquainted with that well-known and common bait the Lug-worm, Arenicola marina, amongst other Polychaet lures, which form part of the group of "marine worms, whose bodies are usually elongated and cylindrical; they either lead a free life swimming
