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Show 1873.] DR. J. S. BOWERBANK ON THE SPONGIADcE. 9 Hab. Unknown (Mr. Thos. Ingall). Examined in the dried state. I received this sponge from my late friend Mr. Thomas Ingall in 1861. He purchased it with other specimens, the localities of which were unknown. The specimen is evidently in a young and somewhat immature state, and it is very probable that its form would undergo considerable modification in a more fully developed condition ; but even in its present state it is a very remarkable species. The surface is even but very rough to the touch, in consequence of the projection of the radii of many of the large bifurcating patento-ternate connecting spicula. Although so young, there are already two well-developed oscular areas upon its surface-one in a rather deep depression, and the other nearly level with the external surface. Very little remains of the dermal membrane ; but what there is of it is crowded with the minute attenuato-stellate retentive spicula, among which there are a very few of the larger subsphero-stellate ones. The acerate tension-spicula are scattered on the surface of the membrane and are rather few in number. The same spicula that occur in the dermal membrane are found dispersed over the surface of the interstitial ones, but they are much fewer in number than on the dermal membranes. It is a remarkable circumstance in this specimen that many of the connecting patenti-ternate spicula, the triradiate heads of which in other species of Geodia are attached to the inner surface of the dermal crust of the sponge, in this one are projected forward to such au extent through the stratum of siliceous ovaria that their radii are seen emerging immediately at the dermal surface, while others are seen at and near the inner surface of the dermal crust. This difference in the disposition of these spicula from those in other species of the same genus may probably be accounted for by the fact that the specimen under consideration is most likely in an early stage of its growth and development, and that in future examinations of larger and more completely developed individuals the connecting spicula will be found occupying their usual positions immediately beneath the dermal crust. The recurvo-ternate spicula occupy their usual position beneath the dermal crust; their long slender shafts are incorporated with the skeleton-fasciculi, their heads appearing in the intermarginal cavities. The progressive development of the bifurcating patento-ternate connecting spicula is exceedingly well illustrated in this sponge. They are first observed to be small and slender with simple patento-ternate radii acutely terminated; and in this form they remain, gradually increasing in length and stoutness until they attain the size represented by fig. 5, Plate II. As they approach their complete state of development the bifurcations of the radii become more or less produced, but frequently in a very unequal manner, as in fig. 6, the furcations being developed on one or two of the primitive rays, while the third remains simple ; but when their |