318 CEYLON PEARL OYSTER REPORT. 



The axis is very calcareous and brittle. 



The polyps on the main stem or branch are more or less restricted to the lateral 

 edges, but on the younger branches they occur on the four surfaces in such a way that 

 they all alternate and appear as if arranged in a spiral manner. They are contained in 

 verruca; which are small, slightly conical and truncated at the top. The polyps 

 themselves are all withdrawn into the verrucas, but they present yellowish-white 

 apices at the opening of the verrucas. Towards the base of the tentacles on the 

 aboral surface two or three pairs of spicules are arranged en chevron, and at their 

 bases a few are arranged transversely so as to form a collar. These spicules are short 

 warty spindles, either straight or slightly curved. 



The cnenenchyma is thin and is composed of two layers of spicules, the outer layer 

 being coloured and giving the characteristic colour to the colony, while the inner layer 

 is colourless. 



In the coloured layer the spicules show a considerable range in shades, varying 

 from a light to a deep amber tint. 



The spicules are spindle-shaped, thick in comparison to length, or slender, and 

 covered with rough warts. The coloured, or outer layer, contains the bigger spicules. 

 Their measurements, length by breadth in millimetres, are as follows : 



(a.) Coloured, 0-3 X 0-075; 0'4 X 0'08 ; 0'22 X 0"05 ; O'll X 0"05 ; (HO X 0-03; 

 0-08 X 0-02. 



(/>.) Colourless, 0-14 X 0'04; 0-175 X 0-04; 010 X 0'035 ; 0"28 X 0'025. 



Order V. STELECHOTOKEA. 

 Section I. ASIPHONACEA. 



Family: TELESTID^E. 

 Telesto rubra, Hickson. 



This species is represented by two fragments, one of which (A) measures only 

 30 millims. in height. 



Specimen A agrees closely with the description given by Hickson. Thus, in the 

 basal portion of the youngest calyces, the spicules are fused to form tubes, the axis 

 has eight longitudinal ribs, and prolonged boiling in caustic potash does not 

 disintegrate it. 



Specimen B seemed at first sight to have a black axis, but this was found to be 

 due to debris which had collected in the hollow tube. 



The whole surface of specimen (A) is covered by an encrusting sponge, which has 

 completely destroyed the ccenenchyma. The spicules of the sponge are monaxonial 

 and triaxonial. 



Locality : Trincomalee. 



