70 



Cortical spicules : (a) Those of the stem are spindles, straight or curved, 

 averaging about 0-48 ram. long, with regularly arranged simple spines ; also a 

 few irregularly branched, flat, smooth, striated forms. 



(b) Those of the stalk are short, thick spindles, which average about 0-30 

 mm. in length, clubs, tripods, discs, three-rayed and globular forms, and 

 numerous irregular forms including variously shaped twins. 



Canal-wall spicules : {a) In the stem there are numerous smooth, flat, 

 spindle- to star-shaped forms with toothed edges. 



(b) Those of the stalk are similar to the preceding. 



Colour — Stalk greyish ; stem, main branches and lower parts of secondary 

 branches pinkish-grey ; upi)er parts of branches and twigs brown ; polyps 

 yellowish-brown. 



Locality : Arakan Coast, 13 fathoms. 



Dendronephthya delicatissima, Henderson. 



This species is represented by a beautiful specimen which measures 5 1 cm. 

 in height and has a maximum breadth of 47 cm. The colony is remarkable for 

 its fine contrasting colours. 



The stalk is of medium length, being 2'5 cm. 

 long, and is rigid. The base is slightly broken, but 

 it is almost certain that it was broad. It is thrown 

 into a number of furrows and ridges, and its upper 

 portion is partly concealed by reflexed lower branches. 

 The polyparium is compact, bluntly oval in 

 shape, and shows a slightly greater growth in one 

 plane ; it is D-shaped in section in the lower part. 

 It consists of a number of main branches which arise 

 from the stem on all sides, and three portions into 

 which the stem finally divides, and which give the 

 apex a blunt, roughly triangular shape. The majority 

 of the main branches arise from the stem almost at 

 right angles. Two of the lowest branches are flat- 

 tened, leaf -like structures almost surrounding the 

 stem, leaving two small free spaces, in one of which 

 there is a small branch with cylindrical lower and 

 flattened upper portion. All the branches are flattened out in the upper 

 portion and then break up into lobes on which the polyps are borne. 



The polyps are arranged in grou])s of three to ten, and are placed, at a 

 right angle or little more, on stalks which may reach a length of 1-5 mm. They 

 are low, oval bodies, 32 mm. high and 64 mm. in maximum width. The 



Fis. 37. D. delicatissima. 



