436 



REVISION OF THE MONAXONID SPONGES, 111., 



HiSTODEKMA ACTiNioiDES sp.nov. (PI. xxii., fig.3; and text-fig.21 ). 



188S. Sti/lotella poli/7nastia (err.), Lendenfeld(27), PL iv., fig.l. 



. Sidfj'oderma navicelligerum R. et D. (err), Lendenfeld(27), 



p.210. 

 The sponge is of massive rounded form, and apparently grows 



attached by a narrow base. From the surface, over its entire 

 extent, arise numerous longer or shorter 

 digitiform, tapering, lax tubular pro- 

 cesses (with thin membranous wall), 

 which somewhat resemble the tentacles 

 of a sea-anemone. Between the pro- 

 cesses, the surface is smooth, and either 

 even or much wrinkled. Oscula appear 

 to be absent. The colour in alcohol is 

 pale yellowish-grey within, and more 

 whitish on the surface. The consist 

 ency is firm, compact, moderately 

 tough and compressible, yet brittle 

 rather than elastic. The dermal layer 

 does not form a noticeable rind, but is 

 thin and closely adherent to the under- 

 lying tissue. 



The single example*(Catalogue, PL 

 iv., fig.l), which is a half-specimen, 

 would, when complete, measure about 

 100 by 80 by 55 mm., in its three prin- 

 cipal diameters. The tubular processes 

 vary in length up to about 20mm., and 

 are 2 to 4 mm. wide at the base. 



The main skeleton consists of non- 

 reticulating fibres running in various 

 a, directions without rei^ular course, and. 



Fig.21. 



Histoderma actinioidei^ _ 



Tylota. a'.Extiemities of scattered between these, of plentiful 

 tylota. MsocheL-earcuatae. ^.^^j^ spicules, and spicules aggregated 



c,Sigmata. 



in bundles and strands. The fibres 



* Another specimen of the species has since been found annoug a collec- 

 tion of sponges belonging to the Department of Biology, Sydney University, 

 and is figured in the present paper. 



