1906.] ALCYONARIANS FROM ZANZIBAR. 409 



stand. Between the larger meshes there are smaller ones on 

 which young polyps are seen. 



The polyps are about 5 mm. in length, with tentacles of 1'5 mm., 

 with about 8 short pinnules in a single I'ow on each side. On the 

 lower pai't of the polyp-body there are no spicules, but just below 

 the base of the tentacles spicules become abundant, at first 

 ai-ranged transversely, then in more or less regular converging- 

 double rows running perpendicularly. There ai'e also a few small 

 irregularly- disposed spicules in the tentacles. 



This species closely approaches Sympodlwm {Alcyoniimi) ftdvum 

 Forsk., but differs in that the upper part of the polyp has 

 no transverse ring of spicules markedly difierent in size from the 

 longitudinally-disposed spicules, in the presence of spicules on the 

 tentacles, and in other features. 



Localities. Wasin, Ohuaka, Kiungani. Common. 



Sympodium splendens, sp. n. (Plate XXIX. fig. 8.) 



A beautiful purplish- crimson colony, spreading around a mon- 

 axonid sponge. The sponge has a tubular fonn (probably due to 

 some foreign axis which has been lost). The basal membrane is 

 about 2 mm. in thickness ; the polyps occur irregularly, some- 

 times almost touching, elsewhere separated by intervals of 4 mm. 

 or so. A fully-extended polyp is 3-3*5 mm. in length ; the 

 tentacles extend for 2-2 "3 mm. further; the average breadth of a 

 polyp is 1"75 mm. 



When the polyp is completely retracted we see a blunt conical 

 calyx (often 2"5 mm. in height), with 8 longitudinal ridges not 

 very sharply defined, and ending in 8 tiiangles. The whole is 

 pvu'plish crimson, except at the summit, where a hint of the 

 yellowish - white polyp is seen. The fully- expanded polyp is 

 almost transparent, for the coloured spicules are not continued 

 beyond the calyx. The flat tentacles have a broad bare streak on 

 each surface ; there ai'e two rows of pinnules on each side, 20-24 

 in each row. There is great variety in the spicules : — (a) Straight 

 and curved spindles with jjrominent warts, usually few and distant, 

 sometimes fairly numerous (0"4 x 0*04, 0*35 x 0'03). (h) Irregular 

 forms: triradiate (0-175 x 0-15), quadradiate (0-2 x 0-125). ' The 

 great majority are j^urplish ; others are transparent, with a con- 

 siderable organic residue, a few incline to red. 



Locality. Ohuaka. 



Family Tubiporid^. 



TuBiPORA CHAMissoNis Ehreuberg. (= Tuhipora miosica Oha- 

 misso.) 



Locality. Large colonies are abundant wherever coral gi'ows : 

 e. g., Prison Island and the reefs south of Zanzibar Harbour, 

 edge of eastern reef of Pemba. Not found at Ohuaka, rare at 

 Wasin. 



