580 DR. R. VON LENDENFELD ON THE SYSTEMATIC [DeC. 21, 



3. Familia Melittionid^, Zittel. 



Forms branched tubes or calyculate structures. Skeleton honey- 

 combed. Cavities traversed by the reticular membrane. The 

 gastral skeleton without scopulse. 



Aphrocallistes, Gray. 



4. Fatnilia Coscinoporid^, Zittel. 



The wall of the calyculate or expanded sponge is traversed by 

 funnel-shaped straight canals, which open alternately on the one or 

 the other surface. Covered only by the perforated limiting mem- 

 brane. 



Chonelasma, F. E. Schulze ; and the fossil genera Leptophragma, 

 Zittel, Ouettardia, Michelin, and Coscinopora, Goldfuss. 



5. Familia Tretodictyid^, F. E. Schulze. 



With irregular inhalant and exhalaut canals, which do not traverse 

 the body transversely, but pass the dense dictyonal skeleton obliquely 

 or longitudinally. 



Tretodictyum, F. E. Schulze ; Euriplegma, F. E. Schulze ; Cyr- 

 taulon, F. E. Schulze ; Fieldingia, Sav. Kent ; and Sclerathamnus, 

 Marshall. 



ii. Tribus Inermia, F. E. Schulze. 

 Without uncinates and scopulse. 



6. Familia MEANDROspoNGiDiE, Zittel. 



The body consists of winding tubes of uniform width. The in- 

 terstices of the tubes form a vestibule space. 



Ductylocalyx, Stutchbury ; Scleroplegma, O. Schmidt ; Margari- 

 tella, O. Schmidt ; Myliusia, Gray ; and Aulocystis, F. E. Schulze ; 

 and the fossil genera : — Placoscyplda, Reuss ; Tremabolites, Zittel ; 

 Etheridgia, Tate ; Gystispongia, Roemer ; Toulminia, Zittel ; and 

 Camerospongia, d'Orb. 



To this Subordo belong the fossil families Ventriculitidse, Stauro- 

 dermidsD, Callodictyonidse, and Cceloptychidae. 



II. Ordo CHONDROSPONGIiE, nov. 



Silicea in which the toughness is caused by the mesoglcea or 

 mesodermal ground-substance becoming cartilaginous, whilst the 

 spicules remain isolated. Spicules tetiaxon, monaxon (tylostylus or 

 stylus), or absent. With spherical ciliated chambers. Sponge gene- 

 rally corticate. 



Comprises the Spiculispongiae of Vosmaer, with the exception of 

 the genus Halisarca, Vosmaer. 



I. Subordo Tetraxonia, Vosmaer. 

 With tetraxon spicules. 



