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Show 1868.] ON BIRDS FROM CONCHITAS. 137 any admixture of earthy material. In the mature state I do not believe that there is any species that is destitute of keratode and composed of sarcode only. I have never yet seen such a sponge ; but in the young and earliest stages of the development of many species we have them, as in Sponyilla and others, simply existing as moving masses of sarcode, which I believe have been designated by observers as Amoeba. In every specimen that I have yet seen that has been designated Halisarca I have always succeeded, by the aid of Canada balsam, in detecting minute siliceous spicula in situ. As regards the animal or vegetable nature of sponges, I may observe that in our investigations of this subject we must take a broader view than that of the ultimate structures of the animal. It is not a cell or a cilium that will decide that question. Nature is not so widely various in her general plan of operations as the world is prone to imagine. The tree, with its almost unlimited capabilities of propagation by seeds, by roots, or by cuttings, and in some cases even by single leaves, is the fit type of the coral, with its innumerable polypes, in each of which the germ of a separate animal is inherent. So it is with the sponge; each morsel of it is the germ of a separate existence; but the combined compound existences within it is in reality the animal. It is a congeries of existences in one. Not that the uniflagellate cells are to be designated as the animal; they are only vital points within, as seeds, buds, or axillary bulbs in plants. The late eminent Surgeon Liston on one occasion invited me to see the ciliated cells from a polypus in the nose of a patient at University Hospital; but no one in such a case would dream of designating man as a congeries of polyciliated cellular animalcula. Such bodies are more or less incidental to the structure of almost all animals ; and in the sponges the living organized mass is the animal, not its incidental parts, as some authors would seem to imply. A knowledge of the structure and offices of such organs in its economy is an important point in the history of the sponge ; but it is the combined structures and working together of the whole organized mass that we must look to for the determination of its character, either as an animal or a vegetable ; and in the performance of its vital functions we have perhaps the most positive and undeniable evidence of its truly animal nature. Its nutrition is, like that of animals, voluntary and at intervals. It imbibes its food through one set of orifices, digests that which it has received, and excretes the rejected matter by appropriate oscula, while in plants these vital operations are involuntary and continuous. 6. List of Birds collected at Conchitas, Argentine Republic, by Mr. William H. Hudson. By P. L. SCLATER, M.A., Ph.D., F.E.S., and O S B E R T SALVIN, F.Z.S. The authorities of the Smithsonian Institution, Washington, United States, America, have most kindly sent over for our inspection a series of birdskins collected at Conchitas, in the Argentine Re- |