55 



Canal-wall spicules : (a) In the stem the spicules are similar to the 

 spicules of the cortex of the stalk, but differ in having fewer rough warts. The 

 si)indles average about 1 -J nun. in length and 0'2S mm. in breadth. 



(//) In the stalk the spicules are similar to those of the canal walls of the 

 stem, and in addition there are numerous spindles, three- and four-rayed forms, 

 discs and plate-shaped spicules which are very flat, show a striated surface, and 

 bear few or no spines. The stalk canal-wall spicules show every phase between 

 blunt spines and simple warts. 



Colour— The stalk, stem and branches are white ; the twigs and polyp-stalks 

 yellowish-white to l)rownish-red, white on the flattened lower branches ; the 

 polyps white. 



Locality : Andamans. 



Dendronephthya merguiensis, Henderson. 



The colony is small, measuring about 4o cm. in height and about 3 cm. in 

 maximum width, much flattened, oval in outline, delicate in appearance. 



The stalk is 1 -8 cm. in height, nearly one- 

 half of the total. It is very delicate but 

 somewhat rigid, stringy in appearance. It 

 gives off at its lower end a number of slender 

 stolons and has its upper portion partly hidden 

 by the reflexed lower branches. 



The polyparium is much flattened and of 

 regular oval outline, the long axis of the oval 

 and that of the stem corresponding. From the 

 lower end of the stem a number of small 

 bi'anches are given off, then two larger branches 

 are given off almost at right angles a little above 

 this, at slightly different levels on opposite sides 

 of the stem and in the same plane. There is no 

 more branching until a little below the apex of 

 the colony, where the stem divides into two main 

 portions which diverge so as to form almost a 

 right angle between them. All these branches 

 are cylindrical in form, and from their surface 

 and the whole stem surface smaller branches are given off which by dividing 

 once, or by repeated divisions, give rise to the short, thick twigs on which 

 the polyps are borne. The lower branches are flattened, leaf-like structures 

 which are reflexed and almost surround the stalk, in collar-like fashion, leaving 

 two small free spaces ; above each of these rises a small branch which shows a 

 slight flattening. 



Fig. 29. D. merguiensis. 



