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Show 1873.] DR. J. S. BOWERBANK ON THE SPONGIADcE. / membranes-tension-spicula fusiformi-acerate, small and few in number ; retentive spicula attenuato-stellate, radii long and slender ; and cylindro-stellate, radii short and stout, minute. Ovaria globose, slightly depressed. Colour cream-yellow in the dried state. Hab. Martinique and Porto Rico, Antilles (Lamarck) ; Island of Dominica, West Indies (Dr. Fleming). Examined in the dried state. The type specimen of the genus is preserved in the Museum of the Jardin des Plantes at Paris. It is subgiobose in form, with numerous slight and irregularly shaped elevations dispersed over its surface ; and it is from 4\ to 5 inches in diameter. There is one large oscular area about an inch in diameter, somewhat sunk beneath the general surface, and contained within a well-defined marginal ring, the greatest diameter of which is about two inches. Nearly the whole of the radial fasciculi of the skeleton have apparently been scooped out, to facilitate the drying of the specimen, through a large hole in the sponge about 1 g inch in diameter ; and so effectually has this operation been performed that the sides of the sponge do not appear to exceed about half an inch in thickness in its dried condition. There is a second specimen of apparently the same species of Geodia in the French Museum, somewhat larger than the type one, varying from 5| to 6 inches in diameter. The form is nearly the same as the first, but the surface more prominently tuberculated, and more conical in form ; but these slight variations are of no importance as specific characters. This specimen, like the type one, has a single nearly circular oscular area, with a well-defined marginal ring, the diameter of which is about 1 \ inch; it has also a large hole about 1 \ inch in diameter; and the interior substance of the sponge has evidently been removed to facilitate the drying of the specimen. These specimens were hitherto considered to be the only two known. Through tbe kind assistance of Professors Milne-Edwards and Valenciennes, I had an opportunity of thoroughly examining their organization; and from them, and from a third one in the possession of Dr. Andrew Fleming, son of the late veteran naturalist, Professor Fleming of Edinburgh, I have constructed the above specific characters. The oscula in Dr. Fleming's specimen are so small as to be scarcely discernible without the aid of a lens. On one side of the sponge they are dispersed ; but on other parts they are congregated in small groups, but not especially so in the depressions of the surface. They are each furnished with a contractile membrane ; some of them were completely closed, while others were more or less in an open condition. The difference in the disposition of the oscula in Dr. Fleming's specimen and those in the French Museum, may probably be accounted for by the younger and less-developed state of the smaller specimen. Unfortunately all the three specimens have much deteriorated, apparently by maceration in water, or by repeated washing; so thai |