26 Proceedings of the Royal Society of Victoria. 



(The term " microtylota " is here proposed for an apparently 

 new type of microsclere consisting of a long slender shaft with a 

 knob at each end). 



Microtylotella giintheri, n. sp. 



Massive, solid and heavy. Vents (in one specimen) few, large, 

 on broad rounded margin. Very hard ; composed chiefly of 

 coarse sand arranged in dense, stout, close-packed, radiating 

 columns, whose ends may form a meandriniform pattern on the 

 upper surface. Colour in spirit sandy brown. 



The spicular skeleton is reduced to insignificance in comparison 

 with the coarse sand, but slender spicules are abundantly 

 scattered through the soft tissues. 



Megascleres, long, slender, nearly straight tylota, with slightly 

 developed heads ; size about 0*28 by 0'003 mm. 



Aficroscleres, {a) very minute, slender isochelse, about 0-012 

 mm. long, of ordinary form like those figured by Carter for 

 Forcepia coiofiensis ; {b) smooth, slender toxa, of extremely vari- 

 able dimensions, sometimes so long and so slightly curved as to 

 resemble raphides ; (c) microtylota, with very slender, straight or 

 nearly straight shaft, which may be very faintly microspined, 

 terminating at each end in a small button-like knob (perhaps 

 slightly toothed); the whole about 0'08 mm. long and 0"0015 

 mm. thick in the shaft. 



I have much pleasure in dedicating this remarkable species to 

 Dr. Giinther, of the British Museum, as a slight recognition of 

 his many kindnesses. 



R.N. 473 (x, 20 f ; "bay"); 757 (s. 5, "vermilion"). 



Genus Hisiodernia., Carter. 



Sponge consisting of a massive body throwing oflf hollow 

 processes or fistula? ; with a more or less strongly-developed 

 cortex of horizontally-placed megascleres. Megascleres usually 

 diactinal, but ranging from tylota to styli. Microscleres isochelse, 

 to which others may be added. 



Siderodernia, Ridley and Dendy, may possibly have to fall 

 under this genus. 



