SPONGIIDA. 469 



Internal structure rendered cavernous by the wide canals of the 

 excretory system ; texture of internal structures moderately tough. 

 Internal skeleton formed of trabeculae and sheet-like expansions 

 some larger trabeculae formed of crossed skeleton-spicules strength- 

 ened by dense sarcode proceed from the interior and support the 

 cortex ; they are from -4 to "8 mUlim. in diameter. A strong cortex, 

 about -8 millim. thick, tough, formed chiefly by the skeleton-spicules 

 much intercrossed, and united by a somewhat dense, brownish, sub- 

 transparent sarcode (becoming less visible when the specimen is 

 dried). Spicules : — (1) Skeleton spinulate, strong, slightly curved ; 

 head oblong, almost oval ; shaft gradually diminishing to about two 

 thirds of its full diameter towards head, and tapering gradually to 

 sharp distal point ; average maximum size "6 by '02 millim. (2) 

 Spinispirular, delicate, composed of about three rather sharp bends, 

 with about 4 to 8 rather blunt spines, "OOSl millim. long, to each 

 bend ; shaft of equal diameter in all parts ; average maximum size 

 •032 by -0016 millim. (exclusive of spines). 



Hab. Thursday and West Islands, Torres Straits, 4-7 fins. ; 

 bottom sand or coral. 



Disfribution. Trincomalee (Garter); GaUe coast, Ceylon (coll. 

 Mus. Brit., ex coll. Dr. Ondaatje). 



The external appearance of this fine species is more characteristic 

 and constant than is usual in the Suberitidae. Mr. Carter has 

 shortly described it, but without name. The largest specimen 

 known to me is one brought by Dr. Ondaatje, Colonial Surgeon, 

 from Ceylon, which measures 225 miUim. by 130 miUim. (9 by 5 

 inches), by 60 millim. (2| inches) in greatest thickness ; it was 

 obtained at or near low-water mark. 



The species is nearly allied to Hymeniaeidon angulata of Bower- 

 bank (Madeira), but has a skeleton-spicule of twice the diameter of 

 the spinulate found in that species. 



The spicules show no striking variation in size ; the length of the 

 spinulate varies from "55 to "63 miQim. in diflGerent specimens ; its 

 breadth and the size of the flesh-spioule are almost constant. 



Colour. This is produced by a number of globular or suboval cells 

 of oUve-green colour throughout, provided with a large nucleus of a 

 darker colour ; they measure about -0095 millim. in diameter, and 

 have a well-defined outline ; they appear to be confined to the 

 mesoderm. 



99. Spirastrella congenera. (Plate XLIII. figs, d, d'.) 



Massive, attached by broad base, tending to rise into pyramidal or 

 cylindrical lobes, each terminated by the vent. General surface 

 even, smooth (in dry state). Colour (in dry state) pale fawn. Vent 

 (in the single dry specimen) oval, 8 millim. in greatest diameter, 

 leading deeply into the body of the sponge, the margin level with 

 the general surface (in the single specimen a tongue-like process, 

 8 mUlim. high, stands at one side of it). Internal structure cavernous, 

 with wide spaces ; texture of internal structures moderately tough. 



