SPONGES FROM COASTAL BEACHES OF N. S. WALES — "WHITELEGGE. 79 



thickness ; the areolation is mostly rounded, the spaces being 

 2 to 3 mm. in diameter. Oscula scattered, about 5 mm. or more 

 in diameter. The surface presents a delicate porous membrane, 

 which is abundantly charged with scattered spicules. Texture 

 spongy, inelastic, and somewhat brittle. Colour yellowish-gray. 



Skeleton consisting of a series of wavy longitudinally arranged 

 whispy fibres, with a moderate amount of pale spongin ; secondary 

 connecting fibres abundant Vjut ill defined, occasionally with three 

 or four spicules in a row, but more frequently consisting of 

 scattered whispy bundles. Main fibres about O'l mm. in dia- 

 meter, and 0'15 to 2 apart. Mesh very irregular, angular to 

 oblong, often tilled in with scattered spicules. 



Megascleres — (a) Strongyla of the fibres and ground substance 

 straight or slightly curved, with well rounded and often inflated 

 ends. Size— 0-21 to 0-25 by 0-007 to 0-009 mm. (b) Slender 

 strongyla, generally straight, with or without oval heads, abundant 

 in the dermal membrane and scattered in the ground substance. 

 Size— 0-15 to 0-2 by 0-0025 to 0035 mm. 



Microscleres — («) Large tridentate isochelse, with but little 

 bent shaft and well developed flukes. Size — 0*025 ram. in length. 



(b) Small isochelfe, probably young forms of (a). Size — 0018 mm. 



(c) Sigmata simple and contorted. Size — 0-035 to 0-04 mm. The 

 microscleres are extremely abundant in all parts of the sponge. 



The larger specimen measures 70 mm. in height, 160 mm. in 

 length, and 125 mm. in breadth. 



Two examples were obtained at Port Stephens. 



Sub-family ECTYONIN^. 

 Myxilla, Schmidt. 

 Myxilla isodictyalis. Carter, sp. 

 Ilalichondria isodictyalis, Carter, Ann. Mag. Nat. Hist., (5), ix., 

 1882, p. 285, pi. xi., fig. 2 ; id., Ann. Mag. Nat. Hist., (5), 

 xvii., 1886, p. 52. 

 Myxilla isodictyalis, Dendy, Proc. Roy. Soc. Vict., (n.s.), viii., 

 1896, p. 30. 

 Sponge compressed, measuring 55 mm. in length, 45 mm. in 

 breadth, and 20 mm. in thickness. The texture is brittle and 

 somewhat bread-like. Colour, dark cream. 



The spicules are as follows : — (a) Smooth styli, often tending 

 towards tylostyli ; generally with a slight bend at the basal fifth 

 or sixth, the rest of the shaft is straight and tapers to within 

 about two diameters of the end, from thence it is abruptly 

 narrowed and acute. Size — 0'17 by 007 mm. (b) Straight 

 smooth tylota, the ends about equal to the middle in diameter. 

 Size — 0-25 by 0005 mm. (c) Isochelae. Size — 0-021 mm. in 

 length, (d) Sigmata, simple and contorted. Size — 0018 mm. 

 in length. 



