OCR Text |
Show 1877.] FIVE N E W SPECIES O F SPONGES. 461 Colour. In the dried state, grey ochreous yellow. Hab. Geelvinks Bay, N e w Guinea (Dr. A. B. Meyer). Examined in the dried state. Type in the Dresden Museum. Dr. Meyer observes, "in life brown." The form of this sponge is that of a closely compressed cup with a considerable complication of parietes on one side ; and it does not appear as if it had been more expanded when in the living condition. It is one foot in height and the same at its greatest expansion, and the pedicel is short and stout. When covered by the dermal membrane, the surface both within and without the cup is smooth and even. Near the base of the sponge there are a few oscular orifices slightly elevated on tumid masses ; but these organs are inconspicuous on the more fully expanded parts of the sponge. When a portion of the dermal membrane, mounted in Canada balsam, was examined by transmitted light with a power of 200 linear, the porous areas seen were large and well defined ; they contain usually one, but occasionally two or three pores, each of which is surrounded by a beautifully regular and very extensive series of apparently minute corrugated radiating lines ; some of these pores are open, while others are completely closed. With a higher power this apparent corrugation is seen to consist of minute slender transparent fibres which freely anastomose with each other in the immediate neighbourhood of the pores ; but subsequently they diverge freely to a very considerable distance from the pore without anastomosing with each other. The skeleton is decidedly that of a Halispongia. The primary or radial fibres are amply supplied with the usual central lines of embedded grains of sand and other extraneous substances, and more especially so at tbe surfaces of the sponge. A few adventitious spicula of various sizes and forms are entangled amid the skeleton-fibres, to which also numerous dark opaque spherical gemmules are attached, varying in diameter from TJQli to y-^^ inch in diameter. The most striking specific characters in this species of sponge are undoubtedly those of the dermal membrane ; and it must be observed that they are very difficult to find without the aid of mounting portions of the dermis in Canada balsam ; and from the extreme delicacy of the radial lines surrounding the pores, powers of from 200 to"500 linear are required to render them distinctly to the eye of the observer. 5. HYALONEMA ANOMALUM, sp. nov. Sponge expansively cup-shaped, sessile (?) Surface smooth. Oscula on the inner or exhalant surface, simple, large and numerous. Pores dispersed, inconspicuous. Dermal system expansible ; connecting spicula expando-quaternate ; radii and shaft attenuating, large and strong. Dermal membrane aspiculous ('?). Skeleton: Cup compressed (?), fasciculated, fasciculi loosely compacted; spicula cylindrical, with clavate or thyrsiform terminations incipiently |