258 CEYLON PEARL OYSTER REPORT. 



slightly larger than in that species and are much less numerous. They have the 

 form of tuberculate dumb-bells. They are fairly abundant in the superficial tissues, but 

 are scantily distributed in the more deeply seated portions of the colony. 



The average size of the spicules is (VI 4 millim. by - l millim. 



As in other species of Alcyonium, there is only one system of canals. This, the 

 internal system, is extremely well developed in the interior of the colony, but becomes 

 less well marked towards the surface of the capitulum. This system consists chiefly 

 of short transverse vessels which connect the coalentera of the zooids (Pratt, 1903). 

 Owing to the great number of zooids, which in this species penetrate deeply into the 

 interior, the longitudinal canals are comparatively few in number. 



This species is characterised by its soft fleshy consistency, its numerous but very 

 minute zooids, the entire absence of ventral mesenterial filaments, accompanied by an 

 abundance of zoochlorelke in superficial tissues, and the small spicules. 



It approaches A. pachycladoa in the absence of ventral mesenterial filaments and 

 in the form of the spicules. It differs however from that species in the texture of the 

 colony, the minuteness of the zooids and in its less numerous but larger spicules. 



Alcyonimn pachyclados, Kltjnzinger (1877). 



Three complete specimens of this widely distributed species were taken from the 

 Gulf of Manaar. 



They are all similar in external form, consistency and colour, but specimens in the 

 Victoria University of Manchester from different localities exhibit considerable variation 

 in these respects. The Ceylon colonies form low, more or less lobate, sessile, encrusting 

 masses, from 10 millims. to 20 millims. high and from 28 millims by 18 millims. and 

 42 millims. by 23 millims. broad. The capitulum has a more or less convex surface, 

 on which are studded, with varying frequency, the short and broad, rounded or 

 conical lobes ; the largest lobe is 7 millims. high and has a basal diameter of 

 8 millims. by 7 millims. These colonies are very similar in external form and 

 character to specimens from the Maldive Islands (Pratt, 1903), China Strait and 

 New Britain, but differ considerably in colour and manner of growth from the 

 arborescent specimens which have been attributed to this species from the Cape of 

 Good Hope (Hickson, 1900). The Ceylon specimens are harder and more brittle 

 than the forms I have examined from other localities, this being no doubt attributable 

 to the great abundance of spicules. 



The Ceylon specimens (in spirit) are of a creamy-white colour with autozooids of a 

 darker shade, and are similar in this respect to the specimens from China Strait. 

 The Maldive specimen (in spirit) is a pale brownish-grey colour, of a darker shade 

 between the lobes. The specimen from New Britain is a uniform grey colour, while 

 some of the Cape specimens are white, some yellow and others red in colour. 



In distribution this species is known from the Red Sea, Maldive Islands, China 

 Strait, New Britain, Cape of Good Hope and now the Gulf of Manaar. 



