Catalogue of Non-Calcarcoiis Sponges. 17 



Skeleton^ the main skeleton is very lax and irregular, consisting 

 of branching, whisp-like, niultispicular fibres, trending in a sinuous 

 manner towards the surface, and branching freely, especially as 

 they approach the surface ; sometimes forming oblique anasto- 

 moses. A large quantity of very pale-coloured spongin invests 

 these fibres. Very numerous megascleres are also scattered 

 irregularly through the ground substance. There is no special 

 dermal skeleton. 



Megascleres, straight, slender tylcstyli, gradually sharp-pointed 

 and with fairly well developed ovoid heads ; measuring about 

 0-2 by 0-004 mm. 



Microscleres, (a) extremely minute and slender anisochelse, only 

 about 0"01 mm. long ; (/;) smooth, slender toxa, gradually sharp- 

 pointed at the ends, measuring about 0'095 by O'OOIT mm.; (e) 

 slender sigmata, simple and contort, measuring about 0*0 12 mm. 

 from bend to bend, very rare. 



J^.JV. 779 (Sorrento Jetty). 



Esperella crassa, n. sp. 



Sponge massive, irregular, lobose or ridged, with vents on 

 prominent parts. Surface covered with delicate, minutely reticu- 

 late dermal membrane, with coarser reticulation of underlying- 

 parts showing through. Texture compact, incompressible, friable, 

 intensely and coarsely sandy throughout. Dark brown in spirit. 



Skeleton. The main skeleton is made up almost entirely of sand, 

 not arranged in definite tracts or fibres, with the very much 

 reduced proper spicules scattered m the soft tissues between. 

 The dermal membrane is free from coarse sand but contains 

 many foreign spicules arranged in a very loose and irregular 

 network. 



Megascleres, very slender styli or perhaps strongyla, commonly 

 slightly curved, measuring about 0'16 by 0'002 mm. Most 

 abundant just beneath the dermal membrane, pointing towards 

 the surface. 



Microscleres, minute, slender, palmate anisochehe, of ordinary 

 form, about 0'016 mm. long. 



R.N. 521 (x, 20 f ; "wood brown, the vents and inner surface 

 sulphur yellow ") ; 939 (x A). 



c 



