372 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



be much larger than the others, it would appear simply as the pro- 

 longation of such a canal. 



The form comes from a different locality from those where the 

 type was taken, and with the difference in canal anatomy are as- 

 sociated other differences. But these, especially the spicule measure- 

 ments, are only such as generally characterize colonies of indi- 

 viduals belonging to the same species but living at some distance 

 from one another. They constitute the now well recognized " geo- 

 graphical mark ". 



Sponge is irregularly spheroidal, 75 mm. in diameter. Upper and 

 latero-superior surfaces bear numerous, 11, apertures, 2-5 mm. in 

 diameter. Several of the larger are oscula. The others, 2-3 mm. 

 wide, are the openings of the poriferous pits. Both are surrounded 

 by spicular fringes, although these in many cases have been nearly 

 rubbed off. The general surface is undoubtedly covered in nature 

 with a scanty furze of spicules projecting about 1 mm., but these have 

 been rubbed off over a large part of the surface, leaving the dermal 

 membrane smooth. The lower surface is covered with projecting 

 bundles of root spicules, which combine to form a tangled mass that 

 covers the base of the sponge to a thickness of a few millimeters but 

 does not form an elongated root tuft. Sponge, dark brown, both 

 internally and at the surface. 



Some of the oscula are the apertures of large efferent canals, which 

 may be as wide as 8 mm., and which penetrate far into the sponge. 

 The lining membrane of the canal for some millimeters internal to 

 the osculum appears porous, although most of the pores are closed. 

 In other cases the osculum leads into a comparatively shallow cavity, 

 on the floor of which open several, 4—5, efferent canals, 1.5-2 mm. in 

 diameter. 



The poriferous pits are smaller than in the specimens of the type, a 

 typical one measuring 8 mm. deep, 4 mm. wide, with an aperture 2-3 

 mm. wide. The lining membrane is abundantly perforated by small 

 apertures, although these are not numerous enough to make the mem- 

 brane sieve-like. Most apertures are 20-30 \x in diameter, but they 

 intergrade with numerous larger ones about 85 \i in diameter. The 

 dermal membrane at the surface of the sponge shows no pores. 



The skeletal arrangement immediately surrounding the oscular 

 canals and the poriferous pits is the same. It consists of numerous 

 radial skeletal bundles which support the lateral wall of canal or pit 

 and project at the surface, forming a marginal fringe round the 

 aperture. This consists chiefly of protriaenes. Internal to the aper- 

 ture are the usual very delicate protriaenes projecting obliquely from 

 the lateral wall. 



The large oxeas of the radial bundles are smaller than in the type 

 specimens. Moreover, they exhibit two well-marked patterns (modes 



