FROM THE INDIAN AND PACIFIC OCEANS. 



29 



breadth 20 cm., sterile stalk 14 cm. Two lower branches flattened, forming two 

 nearly complete semicircles round stem : above this are two lateral branches, and above 

 this again the main stem divides into two branches ; these branches subdivide farther 

 and bear polyps in bundles of 4-8 on stalks of 1-2 mm. Polyp-heads protected by a 

 bundle of 3-5 spicules, of which 2 or 3 project slightly beyond polyp-head. On the 

 lower flattened branches polyps are alternately borne on stalks or are sessile on the edge 

 of the leaf-like branch. The branching is very distinctly in one plane. Spicules of 

 anthocodia arranged en chevron in eight double rows, with 4-6 spicules in each row, 

 all about the same size and not projecting beyond base of lentacles. Spicules of stem 

 and branch : nearly straight spindles covered with warts. Tentacles have a double 

 row of comparatively large thorny spicules, OTxO'02. I am quite unable to find 

 any spicules in the partition -walls, and therefore cannot identify this species with 

 S. involuta (Kuk.). The spicules in both stem and branches are longitudinally 

 disposed; below the polyp-heads they show a slight spiral twist. 



Colour, Extreme base nearly white, all other spicules, stem, branch, anthocodia, and 

 tentacles yellow. 



Sab. Bay of Bengal. 



The following is a list of measurements of a series of transverse sections through a 

 flattened branch, where the alternation of stalked polyps with polyps sessile on the edge 

 of the leaf suggests dimorphism. My series takes in eight polyps — four stalked, and 

 four sessile ; and although the following measurements do distinctly show that the 

 polyps are different in size, it must be borne in mind that the observation is a difficult 

 one ; the polyps frequently are bent, and the figures can only be taken as approximately 

 correct. 



Spiciile-measurements in mm. 



From this it appears that the greatest difl'erence between a long stalked and a short sessile polyp in the 

 stomodffium is 0-036 mm., in the mesenterial filaments is 0-027 mm., in the total length 0-057 mm ; and the 

 least difference in the stomodaaum is 0-009 mm., in the mesenterial filaments 0-013 mm., in the total length 

 0-023 mm. 



The figures in brackets imply that the specimen was somewhat broken and the length had to be either judged or 

 the average taken. 



