354 REVISION OF THE MONAXONID SPONGES, il., 



mine the exact arrangement of the skeleton, and my descrip- 

 tion of this is consequently to be regarded as only approxi- 

 mately correct. 



Description. — "Massive sponges with numerous, irregular, 

 mostly fistular processes arising from the upper surface. The 

 sponge is attached by a broad base and attains a maximum 

 diameter of 300mm. The oscula are situated terminally on the 

 summits of the processes." 



The main skeleton consists of dendritically branching, and 

 occasionally interuniting, stout, plumose "funes" ; and of 

 numerous scattered spicules, the latter here and there form- 

 ing dense masses connecting the "funes." The "funes" are 

 either single fibres, or are composed each of several inti- 

 mately associated fibres ; these fibres consist of a spongin-axis, 

 usually enclosing some longitudinally disposed spicules, and of 

 numerous spicules which project from this axis at varying 

 angles, some of them directed almost perpendicularly outwards 

 in an echinating fashion. At the surface, the columns pass 

 into broad, dense brushes of almost parallel spicules, the outer 

 ends of which, apparently, give support to a dermal mem- 

 brane ; intermingled with the spicules of the brushes, are, 

 sometimes, numerous irregularly disposed spicules. Whether 

 there is a special dermal skeleton, is not quite certain; but, 

 here and there, lying upon the outer ends of the brushes, 

 horizontally directed spicules, forming a thin layer, were 

 observed. 



Spicules. — {a). The spicules which chiefly compose the fibres 

 are straight or very slightly curved, gradually sharp-pointed, 

 fusiform styli with a narrow handle-like basal end, of diame- 

 ter sometimes less than half that of the thickest portion of the 

 shaft, measuring from about 400 to 720 /x in length, by rarely 

 more than 25 /x in maximum diameter. The longest spicules 

 (those, say, of length exceeding 600 yu.) are seldom, if ever, more 

 than 20 /x in diameter ; are always less distinctly narrowed at 

 their basal end than the shorter, and relatively stouter spi- 

 cules ; and are connected by spicules of every intermediate 

 grade with 



