262 



coenencbyma varies considerably. The globular expansion is generally smooth, 

 but forms with a few warts occur, while in others radial striations which dis- 

 appear towards the circumference are not uncommon. The following are a few 

 of the types with measurements in millimetres : — 



(a) Warty spindles in which one-half is replaced by a smooth globular ex- 

 pansion, 0-22 X 0-1 ; globular part, O'l x 01. 



0-25 X 0-15 ; „ „ 015 x 0-15. 



{/>) Similar to (a) but with the warty spindle part bearing two or three 

 branches, 02 x 012 ; 022 x 0-13. 



(c) Similar to (b) but with a further development of warty branches, 

 0-2x018; 018x016. 



Those of the inner layer are : — 



(a) Spindles with tuberculated warts, 0-4 x 01 ; 0-2r) x 0-1. 



(fj) Warty crosses with characteristic x-shaped marking, Oo x 0-3 ; 0-25 x 

 0-2. 



{<■) Irregular warty crosses, 022 x O'l ; 0-3 x 0-15. 



There are also minute crosses, 01 x 01, and spiny spindles, 0-2 x 0-03, but 

 these are not so numerous. 



There are a number of small Ophhiroids attached to tlie branches. 



Locality : Andamans. Marine Survey. 



Previously recorded from Mergui. 



GENUS PLEXAUROIDES, Wright and Studer. 



Plexauroides praelonga (Ridley). Plate IX. tig. 13. 



= (Plexaura praelonga, Ridley). 



A somewhat damaged colony devoid of coenenchyma in several places. It 

 is 120 mm. in height and 70 mm. in maximum bi'cadth. The growth is ap- 

 proximately in one plane, but fusion has occurred between this colony and 

 part of another, so that an irregular mass results. The branching is irregularly 

 dichotomous. The diameter of the main stem is about 275 mm. The axis is 

 horny, hard and black in colour : it has a diameter of 2'25 mm. at the base. 



The coenenchyma is moderately thick and presents a peculiar appearance. 

 The spicules of the outer layer have a projecting thin, smooth, foliaceous ex- 

 pansion. These slightly overlap and give the characteristic structure. On the 

 verrucne similar spicules are arranged circumferentially. 



The polyps are numerous and are closely but irregularly disposed on the 

 stem and branches. The verructe are slightly elevated and give the surface an 

 undulating contour. The distance between the centres of any two varies from 

 1 to 175 mm., but young forms occur irregularly among the larger and more 

 mature polyps. The anthocodiai ar e completely retractile. The tentacles are 



