580 DR. R. VON LENDENFELD ON THE SYSTEMATIC [Dec. 21, 
3. Familia MEeLiTTIONnIp#, Zittel. 
Forms branched tubes or calyculate structures. Skeleton honey- 
combed. Cavities traversed by the reticular membrane. The 
gastral skeleton without scopulz. 
Aphrocallistes, Gray. 
4. Familia Coscinoporip&, 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, Guettardia, Michelin, and Coscinopora, Goldfuss. 
5. Familia Treropictyipa&, F. E. Schulze. 
With irregular inhalant and exhalant 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 scopulz. 
6. Familia MranpRosPoncGip4, Zittel. 
The body consists of winding tubes of uniform width. The in- 
terstices of the tubes form a vestibule space. 
Dactylocalyx, Stutchbury ; Scleroplegma, O. Schmidt ; Margari- 
tella, O. Schmidt ; Myliusia, Gray ; and Aulocystis, F. E. Schulze ; 
and the fossil genera :—Placoscyphia, Reuss; Tremabolites, Zittel ; 
Etheridgia, Tate; Cystispongia, Roemer; Toulminia, Zittel; and 
Camerospongia, d’Orb. 
To this Subordo belong the fossil families Ventriculitide, Stauro- 
dermidz, Callodictyonidee, and Cceloptychide. 
II. Ordo CHONDROSPONGIA, nov. 
Silicea in which the toughness is caused by the mesogloea or 
mesodermal ground-substance becoming cartilaginous, whilst the 
spicules remain isolated. Spicules tetraxon, monaxon (tylostylus or 
stylus), or absent. With spherical ciliated chambers. Sponge gene- 
rally corticate. 
Comprises the Spiculispongiz of Vosmaer, with the exception of 
the genus Halisarca, Vosmaer. 
1. Subordo TeTRAxXONIA, Vosmaer. 
With tetraxon spicules. 
