98 CEYLON PEARL OYSTER REPORT. 



right angles to the main stem, but some are turned upwards and others downwards, 

 interlocking, so that no two overlap. At their point of origin they are about 

 2 millims. in diameter and present the crescentic shape characteristic of the species. 

 A typical branch from the concave side of the stem has a chord of 10 centims., a 

 perpendicular height of 2 centims., and a breadth of 5 centims. The branches bear 

 branchlets, and even secondary and tertiary branchlets, extending in a plane at right 

 angles to the long axis of the branch. The secondary branches arise in a distinctly 

 alternate manner, the planes bearing them 'enclosing an angle of 60. The branches 

 do not all curve in one direction, but for the most part they diverge in pairs, so that 

 the tips of two approximate, enclosing an ellipse. The secondary branches arise in a 

 similar manner, so that the maximum of surface is exposed on the contour of 

 the colony. 



The spines vary greatly in the different parts of the colony. On the black main 

 stem they are disposed very irregularly, and are very small and abundant. This is 

 also the case on the paler branches, and owing to the conical form the whole gives 

 the impression of a moss-rose stem. They are horny in colour and have a black 

 broadened part where they arise from the stem. The smaller branchlets are trans- 

 parent and hollow, being of a golden-brown colour with a faint reddish tinge. Here 

 the spines are much longer, being bluntly conical and pointing slightly upwards. 

 They are arranged in distinct longitudinal lines, which in reality are the result of 

 steep sinistrorse spirals, five or six being seen from one aspect. They are almost 

 equal to the radius of the pinnule and are about one length apart. 



The polyps, which were unknown when Mr. Brook described the "Challenger" 

 Antipatharia, are of two kinds, according to the position in the colony. On the 

 main stem and larger branches they are scattered irregularly on the concave surface, 

 being thus within the general network of the circumference. They are visible to the 

 naked eye and appear as six-rayed stars. They are almost circular, the tentacles 

 being disposed on six radii. The tentacles vary considerably in size, according to the 

 state of retraction. On the pinnules the polyps are arranged on the convex surface 

 and thus all face outwards. They are more rectangular in shape than on the stem, 

 being elongated in the direction of the long axis of the pinnule. The tentacles are 

 disposed in three pairs, those in the sagittal axis being inserted very far down and 

 standing mostly perpendicular to the polyp. The distance between the polyps is 

 approximately the same as the length of a polyp, viz., 0'9 millim. In all cases the 

 mouth is situated on a prominent cylindrical projection, the oral cavity being 

 elongated in the direction of the sagittal axis. 



Cirripede galls are of frequent occurrence, and these are overgrown with the mud- 

 coloured ccenenchyma, also bearing spines. Numerous barnacles are attached to the 

 larger branches. 



Another almost complete colony (C), without the basal attachment, is 22 centims. 

 in height and 9 centims. in diameter at the widest portion. The main stem is bent 



