| OCR Text |
Show 1867.] DR. J. S. BOWERBANK ON HYALONEMA MIRABILE. 21 separated elongated fasciculi reposing on continuous membranes, having the middle of the sponge perforated vertically by an extended spiral fasciculus of single elongated and very large spicula, forming the axial skeleton of a columnar cloacal system." I did not attempt any description of its specific characters, as my object at that time was the description of generic characters only. I now propose entering fully upon the consideration of the minute structures of every part of this complicated and curious animal, and to endeavour to give such descriptions of them as may serve to distinguish it as a species from any other of its congeners. HYALONEMA MIRABILE, Gray. Sponge.-Massive, sessile. Surface even. Oscula mammilloid, more or less elevated ; terminations depressed, corrugated in radiating lines, numerous, dispersed over the surface of a single central elongated cloacal column projected from the middle of the sponge upward ; dermis of the cloaca coriaceous, thick, composed of two layers-outer layer arenaceous, inner layer spiculous; spicula acerate, and cylindro-cruciform, apically or entirely spinous, various in size and proportions : axis of the column a single large spiral fasciculus of very long fusiformi-acerate spicula, each extending from its base to near its apex; spicula asperated near the base. Skeleton lamelliform ; spicula fusiformi-acerate, long and slender, apices obtusely terminated ; or fusiformi-subcylindrical. Defensive spicula :-external inflato-fusiformi-acerate, hemispinous distally; spines ascending. Internal defensive spicula spiculated cruciform ; spicular ray as-cendingly and entirely spinous ; cruciform rays spinous. Tension spicula inflato-acerate, long and very slender. Interstitial spicula attenuato-rectangulated, hexradiate, large and small; and fimbriated multihamate birotulate, in two systems : the primary one very large and stout; hami cultelliform, fimbriated at the base of the inner surface ; shaft cylindrical, entirely tuberculated, tubercles stout; spicula dispersed. The secondary system:-spicula smaller than those of the primary one ; hami very long, apices nearly meeting; neither fimbriated nor cultelliform, congregated. Interstitial spicula cylindro-cruciform, terminally or entirely spined ; radii short and very stout; spines conical, acute, and very large. Retentive spicula quadrihamate, minute ; hami simple, elongate, attenuated. Colour, undetermined in the living state. Hab. Japan. Examined in the dried state. The most perfect specimens I have seen are that in the British Museum (which has the long spiral cloacal column immersed in the basal mass of the sponge to very near its proximal extremity, as represented in the Society's 'Proceedings' for 1857, plate ix., Radiata), and two smaller ones now exhibited (see Pl. IV. figs. 1 & 2). For the loan of the first of these I am indebted to m y friend Capt. C. Tyler, and for the second to the kindness and liberality of my friend Mr. Henry Lee. One other specimen in a similarly perfect state |
