284 



PROF. MARSHALL AND MR. G. H. FOWLER ON THE 



Genus Policella, Gray. 



POLICELLA MANILLENSIS, Kollilcer. 



Of this species there are two specimens ; one from the Andaman 

 Islands, the other from the Mergui Archipelago. The two differ 

 a good deal in comparative firmness or flaccidity, in the varying 

 degree of protrusion of the polypes, in colour, and in other 

 secondary points. The figure given by Kolliker * is, in many 

 respects, intermediate between the two. 



In the Andaman Islands specimen the whole ccenenchym is 

 compact and firm ; the axis is about three fourths the length of 

 the colony ; the autozooids are mostly in a state of complete 

 retraction, and when expanded are smaller than in the other 

 specimen. Along the lower 20 millim. of the rachis the auto- 

 zooids are smaller, almost colourless, and arranged in longitudinal 

 rows, separated by longitudinal folds of the cutis. The siphono- 

 zooids are exceedingly numerous, occupying the whole of the 

 surface of the rachis between the autozooids, except in the 

 lowest 20 millim., where they are absent. There are no calcareous 

 spicules in the rachis, but small otolith-like bodies, O'OOS X 0'004 

 millim., occur in considerable numbers in the deeper layers of the 

 stalk. 



The general colour of the rachis and stalk is yellow-ochre ; the 

 bodies of the autozooids are dark brown, paler at the base, and 

 with yellowish -white tentacles. 



In the specimen from the Mergui Archipelago the ccenenchym 

 is much less firm, the rachis being soft and fleshy, and the stalk 

 only slightly denser. The axis is shorter, hardly more than half 

 the length of the colony, and more slender. The autozooids are 

 larger, and are in a great many cases full}'' expanded ; the tran- 

 sition from the fully-formed ones of the upper half of the rachis 

 to the immature ones at its lower end is much more gradual 

 than in the Andaman Islands specimen. The siphonozooids 

 are smaller and less numerous, and are arranged in longi- 

 tudinal rows between the autozooids. There are a few calcareous 

 spicules in the cutis of the rachis, and numerous otolith-like 

 bodies in the stalk. 



The rachis and stalk are almost colourless; the autozooids are 

 a dark purplish brown in their distal third, transparent at their 

 bases, and have white tentacles. 



Kolliker, op. cii. j)l. xxii. %. 181). 



