Even in worn individuals the traces of the deciduous scales are 

 always present. There an faint transverse lamellar wrinkles : the 



broader extremity i.s not pendulous. 



. r >. Dkscuiption ok a Xkw Gkm s of Sponge (Xenospongia) 

 from Torres Strait. Uv Dr. John Howard <h<\i, 

 F.E.S., V.P.Z.S., Pres. Ent. Soc. etc. 



(Radiata, PI. XII.) 



The Sponge here described was received from Torres Strait with 

 some very interesting Madrepores and Polyzoa. 



It is peculiar as being free like the Funff'etS among the Ma- 

 drepores, but more concave beneath, for having the upper oscules 

 placed in the diverging forked groove of the upper surface, and for 

 having the whole of the under surface covered with a thick coat 

 formed of agglutinated particles of siliceous sea-sand, this coat 

 being much thicker than the sponge itself; and it is probably used 

 to keep it in its place and position at the bottom of the sea. 



Genus Xenospongia. 



Sponge free, discoidal, subcircular, concave below, convex above 

 (rarely lobed on the side) ; the lower surface with a thick coat of 

 agglutinated siliceous sand of nearly equal-sized particles ; the upper 

 surface covered with a white leathery coat formed of felted spicula, 

 studded with round tufts of glassy spicula, the tufts of nearly equal 

 size, formed of numerous very fine transparent filiform spicula, form- 

 ing a roundish brush, each tuft surrounded at the base by a slightly 

 raised edge of the leathery upper coat ; the circumference of the 

 disk is surrounded by a uniform series of similar tufts. The centre 

 of the upper surface is marked with a subcentral impressed groove 

 with raised edges enclosing a series of circular oscules ; this groove 

 sends out branches diverging towards the edge, which are forked 

 and reforked (or rarely trifid) as the disk enlarges, until they ap- 

 proach the edge of the circumference, which is surrounded by two 

 continuous circular grooves, concentric with the margin, containing 

 between them a single circular submarginal series of tufts of spicula. 



When the sponge is young, the forked diverging grooves are few, 

 definite, and evenly spread over the surface of the disk, with several 

 series of tufts between them ; but as the sponge increases in age, the 

 grooves become much more numerous, closer together, nearly pa- 

 rallel with each other, and enclosing only a single series of tufts of 

 spicula between the parallel grooves. 



The substance of the sponge between the grooves is minutely 

 netted, the interspaces of the network being formed of bund! 

 very minute spicula, and with a single series of small uniform-sised, 

 equal, roundish oscules. 



The upper Burface of the adult sponge is sometimes taken pot 



