SPONGtIBA. 



429 



longer than broad, inner margins truncate, as seen from front, 

 tubercle distinct ; shaft slightly and gradually curved ; size -016 

 millim. long : abundant, especially in dermal membrane. (4) Tri- 

 CTirvate, smooth, strong, the curves bold, the points sharp ; size 45 

 by -006 miUim. 



Hah. Prince of Wales Channel, Torres Straits, 7 fms. ; bottom 

 sand. 



A specimen and a fragment in spirit, the former 80 millim. 

 broad by 75 high by 40 thick at present base ; it is almost semi- 

 circular in outline, the round margin uppermost ; it appears to have 

 been torn from a rather larger specimen. 



The presence of a tibiella with smooth ends distinguishes it from 

 aU allied species of Desmacidon (Schmidt) but D. emphysema, Schmidt 

 (JB. Comm. Unters. deutsch. Meer. ii.-iii. p. 118), and JD. physa (id. 

 I. c), the latter of which, however, has the surface of the sponge 

 even and the sponge itself flask-shaped ; in the former the sponge is 

 covered with bubble-like elevations. Desmacidon arciferum, Schmidt, 

 which has a similar tibiella, appears to be an Ophlitispongia, from 

 the strong horny fibre and the echinating arrangement of some of 

 its acuates. D. diance, id., has, besides, the tridentate anchorates of 

 Myxilla and a strongly homy fibre ; and both it and D. anceps, 

 id., possess the forcipiform spicules which occur in Ealichondria 

 forcipis, Bk. 



64. AmpMlectus hispidulus. 



(Plate XL. fig. C ; Piatb XLI. figs, y-y".) 



Erect, clathrous ; formed of a number of irregularly branching 

 and anastomosing masses, their surface more or less covered with 

 low cylindrical or ridge-like elevations. Vents ? Surface hispid with 

 closely set, hair-like terminations of the primary skeleton-fibres. 

 Texture of sponge in dry state firm, elastic, but readily torn, in 

 spirit soft, elastic ;^colour dull pale brown in dry state, in spirit 

 pale pinkish brown. 



Main skeleton of the type known as " isodictyal," viz. consisting 

 of primary lines running straight to the surface, at right angles to 

 it, connected by numerous transverse secondary lines set at right 

 angles to the primaries; distance between primaries at surface 

 about "25 millim., between secondaries '17 miUim., length of the 

 surface processes of primarifis about -3 millim, Fibres formed of 

 pale yeUow horny material, cored by the axial spicules (no. 1) to 

 the extent of about one third of their total thickness in the case of 

 the secondary fibres, about three quarters in the primaries ; margins 

 of horny material clearly seen outside the spicules, except in the 

 surface-tufts of the primaries, which are opaque and dark-coloured ; 

 spicules in series of 3 or 4 in_ the primary, of 2 in the secondary 

 fibres, of about 6 in the dermal tufts of the primaries. Dermal 

 skeleton consisting of an irregular reticulation with polygonal 

 meshes made up of fibres, some of which resemble the primaries, 



