SPONGES.-HALLMANN. 22-1 



Microscleres. — 



(i.) Scarce isochelae palmatce, 8-12 ;t long. 



(ii.) Long slender toxa, tolerably plentiful, of character- 

 istic though somewhat \ariable shape, 160-260 }i in 

 length and, at most, 1.5 /,' in diameter. 



Loc. — Port Jackson (Austr. Mus. Coll.). 



Clathria partita, sp. nov. 

 (Plate xxxii., fig. 3; and fig. 46.) 



Sponge stipitate, ivith few, broad, much compressed, 

 free or coalescent hranclies spread famvise in one plane. 

 Branches transversely jurroived. The dry sponge is 

 covered with a whitish incrustation of dermal spicules, 

 beneath which the surface is dotted with pinhole-like 

 "pores.'' Main skeletoii a very irregular reticulation of 

 horny fibres with loosely {and, in the connecting fibres, 

 usually uni- or bi-serially) arranged spicules. Imvardly 

 the fibres are fairly stout, but superficially they become 

 slender and paucispicular , and form a web-like meshwork 

 in which main and connecting fibres are not distinguish- 

 able. Echinating spicules scarce, comprising both acces- 

 sory and principal styli, as well as occasional intermediate 

 forms. Megascleres : [i] Principal styli, smooth, slightly 

 curved, 240 x 9 y. ; {ii.) acantho styles, seldom more than 

 85 X 6 p; {Hi.) auxiliary styli, smooth, straight, j^o x 

 4.^ ji. Microscleres : Hair-like toxa about 200 ]i long. 



The single specimen is a tall flabellate sponge with an 

 elongated cylindrical stalk and a small number of dichotomous 

 much compressed, strap-shaped branches ; in shape it bears 

 some resemblance to a deeply incised palmatipartite leaf. The 

 branches usually increase slightly in breadth upwards, thus 

 becoming spathulate ; lateral union betw^een them sometimes 

 occurs, and it is possible that in some instances the separated 

 branches may be represented or replaced by a continuous 

 lamina. The specimen measures 400 mm. in total height ; the 

 thickness of the branches at right angles to the plane of 

 branching is about 6 mm. The surface is ornamented with 

 shallow furrows and narrow intervening ridges, running, as a 

 rule, transversely to the margins of the branches. They are 

 never a very conspicuous feature and are sometimes obscure. 

 Thev are most clearlv defined towards the lateral borders of 



