SPONGIIDA. 455 



•11 by '0095 millim. ; and thus gives a wider range to the possible 

 variation in the sizes of spicules within the limits of a species. 



The only locality hitherto known 'with certainty was N.W. 

 Australia. 



Hah. Port Curtis, Queensland (apparently from beach). 



Distribution. F.W. Australia' {Ridley). 



Obs. This specimen most forcibly illustrates some remarks which 

 I published in the 'Journal of the Linnean Society' (Zool. xv. 

 p. 149), on the possible intrusion of extraneous spicules into sponges. 

 The dermis contains, in fascicles and scattered, large numbers of a 

 slender acuate form, which is wholly alien to the sponge, but whose 

 appearance and position are so natural that I found it difficult to 

 establish this fact. Ee-examination of the slide referred to by me 

 (Jj. c. supra, p. 495) as representing a specimen of this species, pro- 

 bably from Freemantle, S.W. Australia, has satisfied me that it is 

 not referable to the species, but to one of those Echinodictya which 

 possess fine acuate spicules in addition to the skeleton acerate (see 

 above) ; the fine acuates were at first regarded by me as adventitious. 



84. Echinodictyum costiferuin. (Plate XLII. fig. r.) 

 ? Spongia costifera, Lamarck, Ann. Mus. Hist. Nat. xx. p. 432. 



Normally probably turbinate, forming an open cup; wall about 3 

 to 8 millim. thick, undulating. Inner surface uneven, beset at in- 

 tervals of about 5 miUim. with pointed monticular eminences, about 

 3 millim. high ; outer surface' proliferating into subdivided ridge- 

 like or monticular eminences, each beset with several sharp points ; 

 these eminences are about 5 to 8 mOlim. high. Surface between 

 eminences on both sides cancellated and more or less cavernous in 

 dry state. Texture in dry etate very harsh to touch, hard, brittle,; 

 colour pale buff-yellow. Main skeleton: — spiculo-fibre compact, 

 no horny matter apparent, but surrounded by yellow saroode ; all 

 fibres echinated by the spined spicules ; consists of (i.) a longitudinal 

 series of stout branching fibres, "032 to •096 miUim. thick, running 

 towards the free e'dge of the sponge, and outwards into its surface- 

 eminences, where they form the sharp points referred to above, and 

 (ii.) an intermediate network composed of meshes varying in shape 

 from subrectangular (square or oblong) to oval and round, the angles 

 always more or less rounded off, greatest diameter from -06 to 

 •15 millim. ; the deeper fibres bear the slender acuate spicule 

 (No. 2) laid along the surface or projecting at very acute angles 

 from it, sparingly. Dermal skeleton as main skeleton, but spicule 

 No. 2 apparently absent. 



Spicules : — (1) Smooth acerate, slightly bent, tapering to more or 

 less sharp points from abovit 3 to 5 diameters from ends ; size "22 to -28 

 by -0079 to -0095 millim. : forms the skeleton-fibre. (2) Smooth 

 acuate, with well-rounded base, tapering gradually to fine point ; 

 size "44 by -005 millim.: on surface of deeper skeleton-fibres. 

 (3) Spined cylindrical, tapering gradually from rounded base to the 

 rather coarsely spined free end ; spines distributed all over spicule, 



