i'OSÏSCillPT I. SCHRAMMEN 's HEXACTINELLID SYSTEM. 115 



Postscript I. 



At a time when tlie priiUiiig of this memoir was iiearlv 

 finished I received A. Schrammen's paper "Zur Systematik der 

 Kieselspoiigien " (Mitth. Roemer-Museum. No. ID. Hildesheim 

 1903). This contains an emendation of the Hexactiiiellidan 

 system advanced by the same writer in "02 and to wliich I have 

 had occasion to refer critically in the foot-note on pp. 23-25 of 

 this Contribution. It is satisfactory to observe that Schrammen's 

 new^ system shows a great approach to that which I have in my 

 mind and of which I have made a brief exposition in the foot- 

 note just mentioned, though it still differs from mine in an 

 important point, as will presently l)e pointed out. 



Schrammen accepts F. E. Schulze's Amphidiscophora and 

 Hexasterophora as the two suborders of the order Hexactinellida, 

 while the little known pakeozoic forms formerly put together by 

 him under a distinct suborder, the Stauractinophora, are placed 

 in an appendix under the families incertœ scdis. This is, I 

 think, quite in accordance with the present stage of our knowledge 

 about the sponges in question. The Hexasterophora are divided 

 by him into two tribes, the Hexactinosa and the Lychniscosa ; 

 the former defined as " Hexasterophora, deren Stützgerüst aus 

 Hexactinen besteht " and the latter as *' Hexasterophora, deren 

 Stützgerüst aus Lychnisken besteht." It is decidedly an advance 

 that the lychniscophorous forms (the Lychniscosa) are brought 

 under the Hexasterophora, whicli they certainly are. The tribe 

 Hexactinosa Schr. is made to comprise three subtribes, the 

 Uncinataria, the Inermia and the Euplectellaria. Of these, the 



