PENNATULLDA OF THE MERGUI AECHIPELAGO. 285 



The principal dimensions o£ the two specimens are as follows : — 





Andaman Islands 

 specimen. 



ivieigui specimen. 







168 



175 





48 



37 





120 



138 





120 



92 





17 



7 





19 



11 





3-5x2-5 



2x18 





8-10 



11 





11 



1-4 





2-6 



4 



Diam. of immature autozooid 



064-0-5 



0-54-0-4 



Diam. of siphonozooids 



04 



016 



Policella tenuis, sp. nov. (Plate XXIII. figs. 22, 23.) 



Colony slender and of somewhat flabby consistency ; nearly 

 uniform in width along its whole length, tapering slightly at both 

 ends. Stalk slightly firmer than rachis, but not separated from 

 it by a sharp line of demarcation. Axis rigid, less than half the 

 length of the colony, quadrangular with rounded angles and 

 slightly grooved sides. Polypes very long and slender, completely 

 retractile, largest about the middle of the rachis, rudimentary 

 at lower end of rachis. Siphonozooids covering whole surface of 

 rachis between the polypes. A few small calcareous bodies in 

 the rachis, and small otolith-like bodies in the stalk. 



Of this form a single specimen was obtained from the Mergui 

 Archipelago. The whole colony, including the polypes, is of an 

 ashen-grey colour ; the rachis is soft, wrinkled, and its surface 

 markedly slimy. 



The axis extends about halfway down the stalk, and not quite 

 halfway along the rachis. 



The great length and slenderness of the polypes, the absence 

 of any line of demarcation between rachis and stalk, the shortness 

 of the axis, and the general flabby condition of the whole colony 

 serve to distinguish the species at once from P. manillense. 



The principal measurements of the specimen are as follows :— 



Length of colony 252 mm. 



Length of stalk 68 



Length of rachis 184 



Length of axis 110 



24* 



