63 



Acanthomuricea spicata, u. sp. Plate IX. fig. 12. 



A small complete colony 55 mm. iu height, greyish- white in colour. 



The branching is mainly iu one plane, but small twigs with two or three 

 polyps arise at right angles to this plane chiefly from the main stem. The 

 branches arise alternately at wide intervals. There is a flat spreading basal 

 attachment. 



The axis is horny, cylindrical, and marked by longitudinal striae. Its basal 

 diameter is 1 mm. 



The verrucse are crowded, and occur all over the stem and branches 

 without any obvious arrangement. On one branch they leave a bnre strip along 

 one side, and bare patches are seen here and there on the stem. There are 

 clusters of verrucas at the origins of small branches, and there are always two 

 divergent verrucee at the tips. The polyps are long, 27 mm. in height even in 

 the partially retracted condition. On the lofty conical anthocodias the spicules 

 are arranged in a crown with long points. The crown consists of four to five rows 

 of small transverse spicules ; each point has three spicules, two converging and one 

 in close connection. On the aboral surface of the tentacles there is a narrow band 

 of longitudinally arranged spicules, and there are smaller forms closely packed on 

 the sides and directed towards the bases of the pinnules. 



The verrucas are from I'S to 2-2 mm. in height and formed of broad spicules, 

 the upper ends of which project slightly and produce a rugged surface. 



The rough bark-Hke coenenchyma is formed of one layer of rough scales — like 

 ctenoid fish scales — which are dovetailed into one another. 



The spicules of the verrucas and of the anthocodise consist of plates with a spine, 

 irregular discs, elongated triangles with broad bases, rods, spindles, and golf-club 

 forms. All are covered l)y warty protuberances. The following measurements 

 were taken of length and Ijreadth iu millimetres : 



1. Plates, rOxO-45; 0-9 x 0-4. 



2. Discs, 0-85 X 0-55; 07x0-35. 



3. Triangles, 0-9 X 0-4; 0-8x0-3. 



4. Rods, 0-6x0-l ; 0'5x0-06; 0-3x0-05. 



5. Spindles, 0-9 X 0-09; 0-4x0-0G. 



6. Golf-club forms, 1-1 X 0-1 2; 0-9x0i. 



The spicules of the coenenchyma are spindles with large expansions (sometimes 

 foliar) on one side, irregular discs, aud somewhat flattened bars. Their measure- 

 ments are : 



1. Spindles, 1-0x0 2; 0-8x0 -2. 



Foliar expansion of .spindles, 04 x 0-12 ; 0-2x0-23. 



2. Discs, 0-6 X 0-4; 0-6x0-35; 0-4x0-4. 



3. Bars, 0-5x0-19; 0-45x0-175. 



