OCR Text |
Show 1869.] DR. J. S. BOWERBANK ON SILICEO-FIBROUS SPONGES. 329 cule, closely resembling those figured by Bowerbank ('British Sponges,' vol. i. figs. 190, 192)." I cannot agree with the learned Professor in this opinion. All the numerous specimens that I have seen, both separated from the sponge and in situ, have their natural basal terminations; and no indication whatever exists of any central hexradiate spiculum from which they may have been separated. A few gemmules were observed adhering to the skeleton-fib res of the inner surface of the interstitial cavities of the sponge ; they are similar in character to those of I. panicea, but in the specimen under consideration they are not nearly so numerous as in the Porto-Rico specimen of that species. IPHITEON SUBGLOBOSA, Bowerbank. Dactylocalyx subglobosa, Gray, P. Z. S. 1867, p. 506, plate xxvii. fig.l. Sponge massive, somewhat cyathiform, sessile. Surface uneven. Oscula and pores unknown. Dermal membrane-retentive spicula spiculated biternate, minute, very numerous ? Skeleton symmetrically radial; areas confluent, somewhat irregular, mostly six-sided, spaces within triangular; skeleton-fibre at the external surface coarsely and irregularly tuberculated ; fibre within the sponge minutely tuberculated ; disposition of the tubercles sublinear. Auxiliary fibres rectangulated hexradiate, abundantly spinous ; radii spinulate. External defensive spicula fusiformi-acerate, very large and long, distal terminations occasionally incipiently spinous. Interstitial spicula rectangulated hexradiate, very slender, radii subclavate, basal ray very long. Spicula of the membranes-retentive spicula spinulo-quadrifurcate and pentafurcate hexradiate stellate, numerous; margins of the spinulate terminations crenulate. Colour in the living state unknown. Hab. Malacca ? (Dr. J. E. Gray). Examined in the state of skeleton. This sponge is in the collection at the British Museum. It is figured of the natural size in the ' Proceedings' of this Society for 1867, plate 27. fig. 1; and at p. 506 of the same volume, Dr. J. E . Gray gives the following brief description of i t : - " Sponge subgiobose, with a deep central concavity above; the outer surface with irregular anastomosing oscules. "Hab. Malacca?" The sponge is based on a fragment of coral, and has very much the form of a young and undeveloped specimen of one of the best description of Turkey sponges, in which the form of the cup is rather indicated than produced ; and it is very probable that in its fully developed state it will be found to be a truly cyathiform species. The expansile dermal system of the sponge has been entirely destroyed ; the oscula and pores are therefore unknown to us; but on one fragment of the outer portion of the skeleton submitted to examination there was a very small piece of the dermal membrane adhering to the surface of the skeleton, and this was densely crowded |