237 



{</) Spindles thickly beset with prickly Wcarts, l-lxO-l.'); 0-9 x 0-275; O'Sx 

 0"25 ; 0'4 X 0-1. A few of these bear a smooth spine. 

 (b) Prickly scale-like forms, OG x 0-25 ; 0:3x01;-). 



{(■) Tri- or tetra-radiate forms with foliaceous expansion much indented: — 

 0'45xO-35 ; foliaceous part 0"15. 

 0-4 x 0-3; „ „ 0-2. 



{(/) Very irregularly branched scales with a few smooth spines, 0'5.5 x 0'35 ; 

 0-4.-) X 0-45 ; 0-45 x 035. 



On the twigs the main types are : — 



(a) Si)indles with three or four spines sometimes bifurcated : — 

 ri X 0"2 ; spines O"! long. 

 0-9 X 0-18; „ 0-13 „ 

 0-7 X 0-15; „ 012 „ 

 (A) Scale-like forms with smooth spines on one side, warty spines on the 

 other : — 



1 X 0'5 ; spines 01 long. 

 1-1 xO-B; „ 012 „ 

 The spicules of the anthocodiaj are warty and spiny spindles, 0-28 x 0-03 ; 

 0-25 x 0-2. 



Locality : Andaman Sea, 79 fathoms. Marine Survey. 



Acis rigida, n. sp. Plate IV. figs. 4 and 9. 



A small complete colony growing on a detached piece of rock covered 

 with Polyzoa ; it is 55 mm. in height and 40 mm. in maximum breadth. The 

 branching is in one plane and quite irregular ; the younger branches and twigs 

 are very slender compared with the older portions. The branches arise at 

 varying angles and are markedly sinuous. The colour of the specimen is 

 crimson-red. 



The axis is horny ; it is thick and hard in the older parts but soft and 

 collapsible in the twigs. The colour varies from yellow to almost white. 



The cffinenchyma is packed with large scale-like irregularly disposed spicules 

 in the main stem and larger branches, but in the twigs they approximate more 

 nearly to spindle forms and are longitudinally arranged. They are so inter- 

 locked as to leave the surface comparatively level and pavement-like. 



The polyps occur for the most part on three surfaces, leaving one aspect of 

 the colony free, but occasionally an intruding polyp breaks the symmetry. In 

 one or two places the polyps are crowded on this surface, but when this is the 

 case the reverse aspect is quite bare. The verrucre are small and wart-like and 

 are supported by spindle-shaped spicules disposed longitudinally and projecting 

 around the margin. They are about 075 mm. in height and the same in 



