MLili.i tiortnniii, Kirkp, 47 



living; exnniple-', but loiiiul .siirr:ic<'.o|»»Miiii;^-< in ft speciincii 

 wliicli liail l)«H»u dropped alive into FltMuiniii;:'^ solution. 



The caiial-sy.stom somewhat rfs»'inl)h'3 that of (JscarelUt, 

 the fla^^ellattHl chambers iiciu;^ oval and ',V.\x 20 /*. 



The skeleton is in the form of more or less iso!ate<l bundles 

 of slender tyles and rhaphides. Tiicrc is always at least ono 

 more or lesa vertical bundle in each node of aponge-tissue ; 

 soinetinips sev<Tal bundles form almost a floor on which tho 

 flagellated chambers rest. There are no special ectosoinal 

 spicules ; micn)rhapliides which were ori;;inally described as 

 possibly ectosomal arc tho eruls of rhaphides which bad been 

 lnoken by the contraction of tho spon;;c iri dryin;^. 



The nucrosclcres are very remarkable, bein^ in the form 

 of oval rings 45 fi long, 30 fi broad, and 3 fi thick at tho 

 rim, with a keyhole sinus on tho inner margin at each end of 

 the lujiu: axis; in some a web-like expansion extends in 

 Irom each lat«'ial marj^MU. 



I had at tirst thought that the siliceous sponge was a 

 (31avulid, but a suggestion made to me by Canon Norman 

 that the oval rings might be of a similar nature to the 

 sphaMancorse of Melonanc/iora is nearer the mark. For at 

 the edge of a very young specimen I have found develop- 

 mental phases of the rings in the form of contorted C-shaped 

 bodies with the free ends crossing each other. From the 

 fact that there is a knob on each side of one of the free ends, 

 I conclude that these spicules are related to anisanchorate 

 forn-s, rather than to sigmas and diancistra (see Lundbeck, 

 Danish Ingolf Exji., Porifera, ii. p. 211); the keyhole sinuses, 

 however, call to mind the notches in ti»e diancistra of 

 Jlanwcnntha. The axial canal is near the thick outer rim of 

 the spicule. Sometimes six or seven rings follow one another 

 in succession at short intervals and parallel — hence the 

 specific name " sculanformis " given below. Possibly one of 

 the functions of these spicules is to keep open the smaller 

 canaliculi and lacunie in tliis highly contractile sponge. 



It is heie assumed that the siliceou-? sponge on the surface of 

 Merli'i is an entity distinct from the calcareous framework. 

 The sponge in question is placed in a new genus, to which 

 I propose to give the name " xVc»7'on/m," in honour of 

 the distinguished Madeiran naturalist Senlior A. C do 

 Noroidia, who treated me with never-failing kindness during 

 my stay at Madeira and Porto Santo. 



NoRONHA, gen. nov. 

 Desmacidonidie with a skeleton formed of more or less 



