STELOSPOTv'GIA. 169 



very wide range of form. The specimens from warmer water — from the 

 northern localities — are slightly rougher than those from the south. 



The colour of the living sponge is violet-brown on the surface, greyish in the 

 interior. Dry skeletons are light chestnu.t-brown, pretty stiff, and elastic. 



The skeleton consists of more or less band-shaped fascicles which extend 

 longitudinally up the middle of the pyriform sponge, following the oscular 

 tube, and emitting branches which curve towards the surface in an elegantly 

 plumose fashion. The fascicles are 0-8-1 millim. broad; the individual main 

 fibres in them are 0"1 millim. thick, and cored with abundant and large spicule- 

 fragments ; they appear fused at intervals of about 0*4 milhm., and are only 

 0'08 millim. apart. The meshes in the fascicles accordingly appear very elon- 

 gate, oval ; they are 0-08 millim. broad and 0-4 millim. long. The connecting- 

 fibres are straight or slightly curved, 06 millim. thick. The meshes are 

 irregular ; the larger ones measure Vo millim. in width. 



The inhalant pores are confined to the outer surface of the sponge, where 

 they lie in small groups of four to eight. They are oval, distended, 0'04— 0-06 

 millim. wide, and lead into slender irregular canals which open out into the 

 wide subdermal cavities, which appear as irregularly tangentially extending 

 canals 1-1*5 millim. wide. From the floors of these the particularly large and 

 conspicuous inhalant stems, about 0*8 millim. wide, arise ; they are straight, 

 extend perpendicularly to the surface down into the interior of the sponge, 

 and give off abundant braiich-canals 0-16 millim. wide. The dermal layer is 

 destitute of ciliated chambers. In the interior they are very abundant, 

 spherical, 0*045 millim. wide, and not provided with special efferent canals. 

 They open direct into the pretty narrow exhalant canals. The latter join to 

 form larger stems, which extend obliquely upward and inward, and open out 

 into the centrally situated vertical oscular tube, which is 8-10 millim. wide. 

 The latter is provided with very conspicuous annular constrictions at short 

 intervals, which often appear drawn out to form sphincter-membranes. 



The membranes which separate the canals of the subdermal system are 

 charged with very abundant oval granular cells. The ova mature in special 

 endothel-capsules which are situated in the small meshes of the fascicle- 

 bundles. 



Whether the sponges mentioned as identical in the list of synonyms are 

 really the same is quite certain only in the case of Carter's >Stelosponf/us levis, 

 the type of which I have re-examined. In identifying Hyatt's forms, I mainly 

 relied on his photographic representations. It seems to me not improbable 

 that Ridley's Hircinia hispida from Chili is a young specimen of this sponge. 



Geogkaphical Distribution. — Pacific Ocean ( United States Exploring Ex- 

 pedition). 



Australia (Cumminr/). North coast of Australia : Northern Territory, S. A. 



