382 COLLECTIONS PKOM MELANESIA. 



fibres rounded-angled meslies, -14 to -21 millim. in diameter, between, 

 the primaries, which are about -42 millim. apart. Skeleton-fibres 

 amber-yellow in colour, usually homogeneous in appearance through- 

 out. Primaries cored to some little distance from surface by a 

 usually single series of small foreign bodies ; secondaries uncored. 

 Saroode dull pale brown, subtransparent. Texture of sponge in 

 spirit very tough and elastic. 



Hob. Alert Island, Torres Straits, 7 fms. 



[Distrihution. " Australian Seas " (Lamarck) ?] 



HIPPOSPONGIA. 



Schuhe, ZeitscL wiss. Zool. xxxii. p. 614. 



Under this head, owing to the sheet-like aggregation of the 

 skeleton-fibres on the different surfaces, and the large tubular cavi- 

 ties formed by the excretory canals, I am for the present including 

 those Spongiidse with mseandrine main excretory canals, as Caeo- 

 spongia cavernosa, Esper, and Spongia intestinalis, Lamarck, as a 

 subdivision of the genus. Characters may, perhaps, in the future 

 be discovered in their soft parts to justify their separation from 

 that genus. The following is a third species referable to this sec- 

 tion of Hippospongia. 



5. Hippospongia derasa*. (Plate XLI. fig. A.) 



Sponge subglobose ; surface and interior of skeleton honeycombed 

 by mscandering and branching excretory canals 2 to 3 millim. in 

 diameter at the surface, opening into larger spaces at a short distance 

 within the sponge. Texture of sponge firm, but elastic, in dry 

 state ; colour buff, becoming ochreous in parts. 



Skeleton at surface between openings of canals smooth and com- 

 pact, as if pared by a knife ; walls of canals smooth. Primary fibres 

 simple, straight, either (1 ) cored and set at right angles to surface, but 

 not projecting beyond it, diameter, where not distended by foreign 

 bodies, "05 millim. ; or (2) not cored by foreign bodies, set approx- 

 imately at right angles to cored primaries, diameter about -035 

 millim. Secondaries forming either subrectangular or irregular 

 meshes between the primaries ; diameter "018 to "022 millim. 

 Diameter of the ultimate meshes -07 to -14 millim. ; distance be- 

 tween primary fibres -18 millim. Fibre dense, homogeneous, elastic ; 

 colour pale amber-yellow. 



Hah. West Island, Torres Straits (washed up). 



The single dry specimen is subhemispherical, and measures 60 

 millim. (2f inches") in length by 35 millim. (1^ inch) in height. 

 The species is most nearly allied to H. (Spongia) intestinalis, La- 

 marck, but has the fibres only about two thirds the stoutness of 

 those of that species, and it is subglobose instead of being elongated 

 and tubular. The texture of intestinalis is coarser and hafsher 

 than that of this species, partly owing to the thickness of the fibres 



* Derado, to rub down, in allusion to the smoothness and compact texture 

 of the surface. 



