OCR Text |
Show 1906.] ALCYONARIANS F R O M ZANZIBAR. 427 Loccdity. Zanzibar; very common among Zostera at low springtide. Previously recorded from Baui, an islet in Zanzibar Harbour. LITHOPHYTUM RAMOSUM Quoy et Gaimard. A well-preserved specimen of this species showed no trace of any spicules even in the canal-walls. The colour of the preserved specimen is yellow-grey. Previously recorded from Zanzibar and N e w Guinea. LITHOPHYTUM THYRSOIDES (Kiikenthal) = AMMOTHEA THYRSOIDES Ehrenberg. Several fine specimens of this common species, all belonging to what Kiikenthal calls the asparagus-like variety-that is to say, with cylindrical stalks rising parallel to one another and united by a common basis. The colour of the preserved specimens is yellowish white, in life it was brownish. One of the distinctive features of this species is that the polyps arise directly from the ends of the stalks. The polyps are from 2-3*5 m m . in length by 1-1*2 m m . in breadth. The spicules of the stalks and polyps are very slender spindles with few w7arts. The following measurements were taken of length and breadth in millims.:-(a) polyp-spicules : 0*09 x 0*01, 012 x 0*012, 0*18 x 0*016, 0*2 x 0*017, 0*25 x 0*016, 0*28 x 0*016 ; (b) stem-spicules: 0*12 x 0*016,0*16 x 0*016,0*3 x 0*02, 0*35 x 0*02, 0*4x0*02. Loccdity. Zanzibar. Previously recorded from Tumbatu Island, on the N . W . coast of Zanzibar, and from the Red Sea. LITHOPHYTUM THYRSOIDES (Kiikenthal), var. DURUM, nov. From a flat spreading base a large number of almost hemispherical lobes arise. Each lobe is closely covered by the projecting calycine portions of the polyps. The colour of the colony is pale orange. The coenenchyma has a gritty structure, with fairly abundant spicules. The spicules of the coenenchyma are long slender spindles, either straight or slightly curved, with small spines arranged irregularly or in whorls. Their length varies from 0*15-0*4 mm., and their width from 0*02-0*03 m m . Loccdity. Zanzibar, among coral, low tide. LITHOPHYTUM FLAVUM (May). The species Lithophytum africanum, L. flabellum, and L. flavum seem to form a close group connected by intermediate forms. There are several specimens in the collection which closely approach L. flavum, but differ from it in being far from rigid and in having few spines on the spicules. W e see no reason to emphasise this quantitative distinction, especially as the boundaries of the three species referred to are somewhat elastic. Their common features are that several cylindrical stalks spring from a common base, that the polyps are borne on short twigs springing from the ends |