430 PEOF. J. A. THOMSON AND MR. W. D. HENDERSON ON [Apr. 10, 



The .spicules of the general coenenchynia are all of one type — 

 spindles covered with i-oiigh warts, which are arranged in regular 

 whorls, and often blunt at both ends. Some of the spicules are 

 yellowish-amber colour, often almost colourless at the tips ; others 

 aie quite coloui'less. Their measurements, length by breadth in 

 millims., are as follows : — 



Ooloiu^ed: 0-2 X 0-05; 0-12 x 0-06; 0-16 x 0-05; 0-16 x 0-04; 

 0-14 X 0-05. 



Colourless: 0-06 x 0-03 ; 0-08 x 0-04 ; 0-12 x 0-05; 0-14 x 0-05; 

 0-1 X 0-04. 



Locality. Wasin Channel, 10 fathoms. 



(B.) — Another colony forms a thin encrustation on a piece of 

 bivalve shell, about 25 mm. by 30 mm., with nine stems rising at 

 various angles. Three of the stems lie on the under concave 

 surface of the shell and keep close to it ; the four longest on the 

 other side extend to 65-80 mm. from the shell. Two have a 

 single branch. The greatest breadth is about 2 mm. There is 

 a slight flattening in the plane in which the polyps for the most 

 part ai'ise. The general colour is a quiet orange. The verrucfe 

 are inconspicuous and for the most part lateral ; some of them 

 show eight distinct marginal lobes. The polyjis are pure white. 

 A longitudinal gi'oove is distinct for a short distance from the 

 base. The spicules are spindles with warts in whorls 0'12 X 0'04, 

 0-14 X 0-04 mm.; and double spindles 0-13 x 0-06, 0-12 x 0-05; 

 and a few small almost orbicular forms. 



This foi'm appioaches S. kbllikeri Wright &, Studer, but diflfers 

 from it in the size and prominence of the verrucfe and in the size 

 of the spicules, but it is connected to that species by Suberogorgia 

 kdUikeri, vai-. ceylonensis. But the Zanzibai' form has smaller 

 verrucae and spicules than the Ceylonese variety, and the series 

 may be regai'ded as illustrating pi'Ogi-essive variation. 



Locality. Kokotoni Harboui-, Zanzibar West, 5 fathoms. 



Family Melitodid^e. 



Wrightella erythema Gray = MoPSEA erythr^a Klunzinger. 

 (Plate XXVIII. fig. 10.) 



Small, irregularly branched, I'ose-red colonies, fixed to coral. 

 The branches are not always confined to one plane. The following 

 measurements were taken of height and breadth in millims. : — 

 15x23; 23x8; 15x8. The specimens agree well with Klun- 

 zinger's description of Mopsea erythrcea, e. g. in the presence of a 

 single red spicule at the base of each tentacle and in the dimensions 

 of the spicules generally. 



Localities. Wasin, low tide, gi-owing on coral ; Prison Island, 

 Zanzibai- Hai-bour. Pi-eviously i-ecoi'ded from the Red Sea. 



In the Aberdeen University Museum there is a specimen 

 fi-om Samoa which is superficially identical with these. It is 

 labelled Mopsea erythrcea. 



