SiMPS'JN — A lt(Wini.(»l Oj' llic doiiloiiclliddC. 353 



tlirougliouL llic colony, being sliglilly thinner in Llic older portions. Tlie 

 surface is fmcly granular. 



The general colour of the colony is ochreous-yellovv ; Ijut the tips of the 

 verrucae and the anthocodiae are white. 



The polyps are distributed in two longitudinal series situated laterally — 

 that is, on the aspects perpendicular to the plane of ramification. In each 

 series there are from three to four irregular rows. The two bare spaces are 

 quite distinct, and only here and there are median depressions to be seen. 



The verrucae vary considerably according to the stage of retraction. When 

 expanded they are mammilliform, are directed upwards, and adpressed to the 

 coenenchyma. This is well seen near the tips of some of the smaller branches 

 where the coenenchyma is relatively thicker and where they are depressed 

 into the coenenchyma (fig. 98). When partially retracted they are wart-like 

 or sometimes like short truncated cones standing perpendicular to the 

 coenenchyma (fig. 99). When still further retracted they appear as small 

 I'ounded projections or may be even sunk beneath the surface of the 

 coenenchyma (fig. 100). 



In all stages an eight-rayed figure is discernible. They are about 1 mm. 

 in diameter, and may attain a height of over 1 mm. 



Two large main canals corresponding in position to the bare tracts are 

 plainly visible in a cross-section. The small canals are very numerous 

 owing to the large number of the polyps in a transverse row. 



The axis is cylindrical and calcareous. It is about 3 mm. in diameter at 

 the base, but gradually tapers to an almost hair-like fineness. It is composed 

 of concentric laminae. The surface is greenish-brown in colour, but towards 

 the centre it is whiter owing to the greater amount of calcareous matter; there 

 are indistinct longitudinal striae. 



The spicules (fig. 101) are "pale yellow or colourless; they consist of the 

 following types, of which the measurements in millimetres are given : — 



(ft) Large double-clubs, with almost hemispherical ends, and a very .short 

 median constriction : 0-07 X 0-035 ; 0'07 X O'Oo ; 0065 x 004 ; 

 0-06 X 0-04. 

 {!}) Smaller double-clubs with more openly waited heads and a longer 



constriction : 0-045 X O'Oo. 

 , (c) Elongated double-clubs with comparatively few irregularly distributed 

 ■ warts : 0-08 x 0-023 ; 008 x 0-02 ; 0-06 x 0-015. 



{(I) Spindles (these may be modifications of type ic) in which the con- 

 striction is not visible) : 0-09 x 0-02. 



Locality. — Andamans. 



[8^2] 



