312 

 GENUS POLICELLA, Gray. 

 Policella australis, Gray. 



With this imperfectly described species we have identified a portion of a 

 colony consisting of part of the rachis, 30 mm. in length, from which the axis 

 projects about 20 mm. The diameter of the rachis is 6 mm. The axis extends 

 to the very tip of the colony ; it is quadrangular in section with each surface 

 equally concave; the breadth is almost uniformly 1"5 mm. The polyps are 

 wholly retractile within a soft cup-shaped verruca-portion 1 mm. in height and 

 1 nmi. in diameter. The body of the l)olyp is about 15 mm. in length. The 

 tentacles ai'e 1"5 mm. long ; they are very broad and bear two single rows of long 

 pinnules. There are eight distinct bands on the verrucai which, when the 

 latter are closed, form eight lobes around the circular opening. These are con- 

 tinued into the polyps and appear as distinct ridges and furrows, the ridges 

 corresponding to the tentacles. There is a marked inequality in the size of the 

 polyps, all stages of growth being clearly visible ; some with minute tentacles 

 scarcely protruding beyond the surface of the coenenchyma are hardly larger 

 than the siphonozooids. Numerous small circular siphonozooids, showing an 

 eight-rayed figure, are prominent among the larger polyps. The following are 

 some of the measurements of spicules in millimetres : — 



(a) Biscuit-shaped, 01 x 005 ; 0-09 x 0-05 ; 008 x 0-04. 



(h) Almost square forms with x-shaped marking, 008 x 0'06 ; 0'06 x 0'06. 



The general colour is bluish but the tentacles are yellowish-brown ; in some 

 cases the pinnules are pale yellow ; the siphonozooids are marked by eight white 

 muscular bands radiating from the circular opening. 



This species differs from /-'. iiKmiUensis in (1) the much smaller size of the 

 polyps (1-5 mm. instead of 12 mm.) ; (2) the presence of spicules in the cortex of 

 the club ; and (3) the shape of the spicules. 



Locality : Andamans. 



Previously recorded from Shark's Bay, Australia. 



