In the sea of Japan is found a very remarkable sponge, generally known by the name of _Hyalonema_. It is a bundle of spicules like threads of glass, which seem artificially tied together, and on the surface of which we regularly find a polyp of the genus _Polythoa_. The nature of this sponge, and its relations with the polyps which surround it, have been discussed for many years. Ehrenberg had recognized the polyp Polythoa around the spicules, but the Hyalonema was considered by him as an artificial product. The _Polythoæ_ were regarded as only a case in which had been placed this bundle of spicules. The learned microscopist of Berlin had even thought that he had found the proof 65 of this opinion in the presence of woollen threads which were observed in a specimen which Mons. Barbosa du Bocage had sent him from Lisbon. Woollen threads had indeed adhered to the spicules of Hyalonema, but they came from the fishermen, who, when they drew these sponges from the water, placed them carefully in their bosoms under their woollen jerseys. Dr. Gray, of the British Museum, considers the sponge as a parasite of the Polythoa, and that the bundle of spicules belongs, not to the sponge, but to the polyp. The most learned naturalist on the subject of sponges, Mr. Bowerbank, expresses a different opinion. The sponge and its spicules, according to him, are but a single body, and the polyps are only a part of it. The supposed polyps would only form a cloacal system for the use of the sponge colony. Valenciennes, guided no doubt by the observations of Philippe Poteau, was the first to recognise the nature of the sponge and its spicules, but it is to Max Schultze that we must give the credit of distinguishing the true character of this extraordinary marine production. He has shown that the bundle is formed by the extraordinarily long spicules of the sponge, and that the polyp establishes itself upon it, by forming a sheath around the bundle. The fact is no longer doubted by any one, that the long spicules form part of the sponge, and that the polyp establishes itself on a part of the colony. But science rarely advances by a single stride, and Max Schultze, like his predecessors, mistook the top of the sponge for 66 the bottom; Professor Loven has shown the true pose of the Hyalonema, and this he has effected by means of a small specimen from the Northern Sea. Semper found a new OEga, to which he gave the specific name of _Hirsuta_, in an enlarged canal of the new Hyalonema of the Philippine Islands, which he dedicated to Mons. Schultze.