772 NEW GENERA OP MONAXONID SPONGES, 



Genus Paeacobnulum, gen. nov. 



Definition.— Desmacidonidae typically of massive or encrust- 

 ing habit, in which the microscleres, when present, are isochelas 

 palmatae and (or) toxa, and the megascleres are of two kinds, 

 viz., smooth amphistrongyla or amphitornota (perhaps always 

 with spinulous extremities) forming the main skeleton, and 

 small acanthostyli, acanthoxea, or acanthostrongyla occurring 

 scattered. 



Type, P. dubium Hentschel (10). 



I define this genus to comprise, in addition to Hentschel's 

 Cornulum dubium (which is from the Arafura Sea), two other 

 species, both imperfectly known, viz., Cliona purpurea Han- 

 cock, — lately referred by Kirkpatrick (11) to his genus Dys- 

 cliona, but subsequently found by Topsent (22) to possess iso- 

 chelae palmatae and toxa, — and Suberites fuliginosus Carter. 

 The last-named (the locality of which is doubtfully given as 

 Torres Strait) is possibly without microscleres, inasmuch as 

 Carter makes no mention of their presence; nevertheless its 

 considerable resemblance to the other two species — and more 

 especially to P. purpurea — in the matter of megascleric spicu- 

 lation, points to the probability of its close relationship thereto. 



Paracornulum appears to stand in the same relation to Cor- 

 nulum as Histodermella Lundbeck (14) to Histoderma. 



Genus Megaciella, gen. nov. 



Definition. — Desmacidonidae in which the microscleres are 

 isoehelae palmatae and non-spinulous toxa (the latter in part 

 attaining to extreme length), the main skeleton is an irregular 

 and confused arrangement of very long smooth styli united 

 by a minimal amount of spongin, and the only additional 

 megascleres are dermal amphitylota, typically with spinulous 

 extremities . 



T y p e, M. pilosa Ridley and Dendy ; the only species. 



Amphilectus pilosus Ridley and Dendy (17) bears in many 

 respects considerable resemblance to two species at present in- 

 cluded in the genus Artemisina, viz., A. anneetens Ridley and 

 Dendy and A. strongyla Hentschel (11), — and, indeed, is espe- 

 cially distinguished from them only in the fact that its toxa 

 are without spinulous extremities and are in part transformed 

 into oxea-like spicules of extraordinary length. In view, how- 

 ever of the constancy of form maintained by the toxa through- 



