THE ALCYONARIA OF THE MALDIVES. 521 



Canal Systems. The superficial and internal canal systems are both extremely well- 

 marked. Near the surface the vessels are very large (fig. 17) compared \vith those of other 

 species. They are much branched and form an intricate network. The large transverse 

 vessels run immediately below the siphonozooids and their lumen is continuous with their 

 coelenteric cavities (fig. 19). They also communicate with the vessels of the internal canal 

 system and directly or otherwise with the coelenteric cavities of neighbouring autozooids. 

 The breadth of the transverse vessels is -07 — 3 mm. 



The species is characterised by (1) the tough fleshy texture of the colony; (2) the 

 small size of the tuberculate spicules; (3) the siphonozooids less degenerate than in other 

 species ; (4) the superficial and internal canal systems extremely well-marked ; (5) zoochlorellae 

 less numerous than in any other species in the collection. 



9. Sclerophytum densuni (= Lobophytum densum Whitelegge, 1897, p. 219, figs. 19 — 22), 

 PI. XXIX. fig. 18, PI. XXX. figs. 20—22. 



One complete specimen over the edge of a shoal fi-om Addu Atoll, at a depth of 

 11 fathoms. Several fragmentary specimens fi-om shallow water fi-om the western reef of 

 Hulule, Male Atoll. Two fragments from 25 fathoms, Miladumadulu Atoll. One complete 

 young specimen (fig. 18) from 34 fathoms, Felidu Atoll (this specimen has not yet lost its 

 mushroom-like form although lobes have gro^vn out from the margin). 



The specimens vary considerably in shape and size, are all hard and brittle, and their 

 surfaces rough to the touch. The capitula of mature specimens have numerous lobes, which 

 vary in size in specimens from different localities. In many cases the margin of the 

 capitulum has no seam, so that but for the presence of zooid apertures on its surface, the 

 capitulum passes almost imperceptibly into the stalk. 



I have compared these specimens with others from Funafuti, China Seas, and British 

 New Guinea and find them to agree fairly well in all essential particulai-s. The species 

 is the commonest in the collection and appears to be the most widely distributed of the 

 genus. Its bathymetric range from shallow to fairly deep water is very interesting. The 

 colour in spirit varies in individual specimens, some are dark brown, some are dark yellow, 

 while others are greyish-bro\vn in colour. The spirit in which the specimens had been 

 preserved had a distinct greenish tinge, which may be dvie to the solution of green colouring 

 matter in the zoochlorellae, as they are very numerous in the canals and endodermal tissues 

 near the surface of the colony. 



The spicules of this species are described and figured by Whitelegge. As they do not 

 differ in any important respect from those of other species, they may be regarded as being 

 fairly tj^ical of the genus (fig. 20) if we except Sc. durum which apparently has no branched 

 tuberculate spicules. Minute clubs and spindles are crowded near the surface. The most 

 common tuberculate spicules are 2 — 3 mm. in length. 



The mesogloea is of a dense tough nature, stains very readily, and is of a yellowish- 

 brown colour in spirit specimens. 



The autozooids are very numerous, regularly arranged on the lobes, and apparently 

 just as abundant in the furrows between the lobes. The diameter of an autozooid cavity 

 (fig. 22) is greatest just below the surface and averages '75 mm., in the stalk being slightly 

 reduced. 



G. IL 67 



