SPONGES. 123 



arrangement of the main skeleton, the usually stout and distinctly headed tylostyles, 

 and the slender, more or less elongated spirasters. 



I propose to regard Professor HERDMAN'S specimens as belonging to four varieties 

 of the species, which may be distinguished as trincomaliensis, tiibulodiyitata, fungoiden, 

 and gallensis respectively. 



Spirastrella vagabunda, var. trincomaliensis, RIDLEY. 



1882, " Suberites, 1 sp., undescribecl, Trincomulee," CARTER (33) ; 1884, Spirastrella 

 vagabunda, var. trincomaliensis, RIDLEY (16) ; 1886, Suberites trincomaliensis, 

 CARTER (20). 



The single specimen in the collection evidently agrees very closely with the 

 specimen examined by CARTER and RIDLEY. It consists of a massive base rising up 

 into a few short, stout, finger-shaped processes. The surface is sub-glabrous, but 

 slightly corrugated vertically; not warty as described by CARTER (this character 

 having probably been due to drying). The colour (in spirit) externally is nearly 

 black, with a greenish tinge, internally dark greenish-brown. Texture compact 

 throughout, but fleshy and fairly compressible, with little or no imbedded foreign 

 matter. The exhalant canals are (in spirit) extremely narrow and surrounded by 

 gelatinous tissue almost free from spicules ; they run vertically upwards through the 

 finger-shaped processes in considerable numbers and probably open by minute vents 

 (now nearly all closed) at the apices of these projections. Greatest height of specimen 

 56 millims. ; greatest breadth of massive base 52 millims. ; length of finger-shaped 

 projections about 23 millims. 



The skeleton is a very dense and confused reticulation of megascleres, interlaced in 

 all directions. On the surface some of them form, in places at any rate, very poorly 

 developed surface brushes. 



Spicules. (1.) Styli and tylostyli ; moderately stout, usually more or less curved 

 or crooked ; apices, and heads when developed, very variable and apt to be irregular ; 

 size of fully grown spicule about 0'62 millim. by 0'00'J millim., but variable. 



(2.) Spirasters ; not very abundant and varying in form from the ordinary zig-zag 

 to one with a simply but strongly curved axis with blunt projections on the convex 

 side; length about 0'012 millim. These spicules agree closely in form and size with 

 those iu Mr. CARTER'S preparation, although a good deal shorter than in the type of 

 the species (according to RIDLEY'S measurements). 



R.N. 52 (Gulf of Manaar). 



Spirastrella vagabunda, var. tubulodigitata, uov. 



In this variety the sponge consists of hollow, finger-shaped processes or " fistulas " 

 rising from a sandy base to a total height of about 50 millims. Each process contains 

 several wide, longitudinal exhalant canals, separated from one another by narrow 

 partitions, and usually ends in a single conspicuous vent. The colour varies from 

 light to dark grey. 



K '2. 



