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Show 1869.] DR. J. S. BOWERBANK ON SILICEO-FIBROUS SPONGES. 83 by the acid imbedded together in their natural conditions in the membranes of the animal, this at once removes all doubts respecting their really appertaining to the animal under consideration. In a small fragment of the skeleton from the inner surface of the sponge near the base I found portions of the interstitial membranes falling the areas of the network of the skeleton in a good state of preservation ; they were coated with dense yellow sarcode, in which were a considerable number of trifurcated hexradiate stellate spicula completely imbedded ; but I could not detect any of the minute attenuato-stellate, the equiangular triradiate, or the small acerate spicula; it may therefore be fairly inferred, from their absence iu the interstitial membranes, that the latter three forms appertain more especially to the dermal one, in which they occur in such abundance. In the Museum of the Jardin des Plantes at Paris there are two very interesting specimens of Dactylocalyx pumiceus; one is a small and apparently young specimen, the other a tall ewer-shaped specimen in a well-developed adult condition. The first of these two specimens, I was informed, had not been in the possession of Dr. Lacaze-Duthiers more than a few weeks previously to m y seeing it. It was labelled "Iphiteon panicea, Valenciennes. La Martinique." It is 2f inches in height, and the same in diameter at the top of the cup. It is based on the edge of a flat piece of what is apparently tufa. In form, it is a symmetrical cup without a pedicel ; the base is about 1\ inch by 1 inch in diameter. The thickness of the cup at the margin varies from a quarter to rather exceeding half an inch. On the outer surface there are deep channels running most frequently in a longitudinal direction, varying in width from about 1 to 2 lines, and in length from | inch to 2 inches; and where they are not present, their places are supplied by round or oval deep apertures. On the interior surface there are also 9 or 10 lines of large round or oval apertures radiating from the base of the cup to the margin. Many of these deep interstitial cavities pass entirely through the sides of the cup, so that they are common to both internal and external surfaces. In some of these cavities on the inside of the cup there were one or two long slender spicula, the whole lengths of which could not be seen. The structural peculiarities of the skeleton agree perfectly with those of the type specimen of Stutchbury's genus Dactylocalyx, and the specific characters, as far as they were present, with the species pumiceus. The specimen has been too well washed, to make it look beautiful; but notwithstanding this injudicious treatment, I found, in the minute section of the skeleton, made at right angles to its surface, several little groups of spinulo- trifurcated hexradiate spicula imbedded in the remains of the animal matter. The second or ewer-shaped specimen is 14 inches in height; its upper margin is not circular, but has one portion of its circumference bent outward and downward like the lip of a large water-ewer. At this depressed part it is 12% inches across ; and at right angles to this line the measurement is 10 inches. It is labelled "Iphiteon panicea " from " Martinique par M . Ple'e 1829." It has no part |
