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Show 1875.] SILICEO-FIBROUS SPONGES. 275 skeleton-fibre, but it differs essentially from it in the form of its reticular arrangement. I have named the genus after m y late friend Mr. Henry Deane, to whom I am indebted for m y knowledge of the sponge. DEANEA VIRGULTOSA, Bowerbank. Sponge sessile (?), virgultose, solid, irregularly cylindrical. Surface even. Oscula, pores, and dermis unknown. Skeleton symmetrical ; fibre cylindrical; central canals large and very distinct. Colour, in the dried state, amber-brown. Hab. West-Indian seas ? Examined iu the skeleton condition. All that remains of this interesting sponge is unfortunately its well-washed skeleton, so that little more can be said of it than what apertains to its generic characters; but these are fortunately very distinctive. The specimen is 11 inch long, and of an average diameter of about 2 lines. Which has been its basal end cannot be determined, as both are broken terminations. The substance of the sponge is very compact, there being no central cavity. There are no indications on its surface of oscules, and not the slightest remains of either dermal membrane or sarcode. When a section of the sponge is made at right angles to its long axis, mounted in Canada balsam and viewed with a power of 100 linear, its structure is beautifully displayed. Its singular confluent rotulate rete is as regular as that of Iphiteon, described and figured in the 'Proceedings' of this Society for May 1869, p. 323, pl. xxi. figs. 1 & 2. No other form of structure occurs in the skeleton ; and whether we view a transverse section, a longitudinal one, or the surface of the sponge, the same rotulate structure is presented to the eye. The canaliculated structure is very strongly produced. The canals radiate from the axis of each rotulum, and usually appear to be continuous through the whole of the skeleton-structure; occasionally, but not frequently, a single ray will be entirely destitute of the central canal; but this is the exception, not the rule. The skeleton-fibres vary in diameter from -^g inch to -^4^ ; but the general average is about -^to hich. The central canals are large in proportion to the size of the fibres ; their range in diameter is from _.0iffT5. inch to -3^3-3 incn> but their average diameter is about T^Q-Q inch. They are not always in proportion to the size of the fibre, the largest canals being frequently in the smallest fibres. Since the above description was written I have received a small fragment of another specimen of the sponge. It is a piece of a similar small cylindrical mass, about 3 lines in length and rather less in its diameter. 1 n this specimen there are remains of sarcode thinly coating some of the skeleton-fibres ; and in many of them the canals are lined with a sarcodous membrane of a dark amber-brown colour, a strong evidence that the sponge was in a living state when taken. No spicula of any description could be detected in any part of the 18* |
