BY E. P. HAI.LMANN. 773 



out the several species of Artemisina, it seems advisable to con- 

 tinue to regard them as an essential characteristic of that genus. 

 Consequently, as there is no other established genus to which 

 Amphilectus pilosus might be referred, a new one for its recep- 

 tion is required. 



Genus Tenaciella, gen. nov. 



Definition.— Desmacidonidae in which the microscleres are iso- 

 chelae palmatae and toxa, the main skeleton is a reticulation of 

 strongly developed spiculo-spongin fibre, and the megascleres 

 are smooth styli incompletely differentiated into three kinds 

 occurring respectively (i.) within the fibres, (ii.) interstitially 

 and subdermally, and (iii.) at the surface, directed perpendicu- 

 larly thereto, forming a dense dermal skeleton. 



Type, T. canalicnlata Whitelegge (23); the only species. 



This genus differs in no essential respect, save in the absence 

 of acanthostyli, from Tenacia 0. Schmidt as defined above. 



Tenaciella canaliculata Whitelegge. 



(PI. xxxvi., figs. 1, 2; PL xxxvii., fig. 1; Text-fig. 1.) 



1906. Esperiopsis canaliculata, Whitelegge, Austr. Mus. Mem., 

 iv., Part 9, p. 471, PI. xliii., fig. 7. 



External characters. — The sponge is erect, stipitate, ramose, 

 with from few to numerous, cylindrical to irregularly subcylin- 

 drical, occasionally anastomosing branches, varying from 6 to 

 11mm. (but usually about 8 or 9mm.) in diameter (PI. xxxvii., 

 fig. 1). Of fifteen specimens available, the largest measures 

 195mm. in total height. The length of the branches seldom ex- 

 ceeds 100mm., and is usually less than 65mm. ; and the stalk, 

 which is no stouter or only slightly stouter than the branches, 

 may reach a length of 60mm. The mode of branching is such 

 that successive branches tend to be given off in the same plane, 

 with the consequence that sparsely branched specimens are often 

 somewhat flabellate. The consistency of the sponge in alcohol 

 is tough, compressible and resilient, and the colour brownish 

 grey; dry specimens are slightly brittle, and their colour on the 

 surface is pale brownish or yellowish grey. 



The dermal membrane is exceptionally well-developed, form- 

 ing a firmly and closely adherent, not very tough skin, about 

 5'inm. in thickness. In dry specimens undamaged by macera- 



