94 PORIFBRA. 



Fam. 1. Tetillidae. The characteristic megasclere a protrisene. Tetilla 

 0. Schm. ; Chrotella Soil as ; Cinachyra Soil. ; Craniella 0. Schm. 



Fam. 2. Samidse. Characteristic megasclere an amphitrisene. Samus Gray. 



Tribe 2. ASTROPHORA. One or more of the microscleres is an aster. 



Fam. 1. Theneidae. Microscleres are spirasters or amphiasters, and oxyasters 

 or microxeas. Without cortex. Thenea Gray; Characella Soil.; Pcecillastra 

 Soil.; Sphinctrella 0. Schm.; Triptolemus Soil.; Stceba Soil.; Nethea Soil.; 

 Placinastrella F. E. Sch. 



Fam. 2. Pachastrellidae. The chief megascleres are calthrops; trisenes 

 absent. Microscleres may be spirasters, spherasters, or microrabds. Pachastrella 

 0. Schm.; Derdtus Gray ; Calthrofella Soil. 



Fam. 3. Stellettidae. Euasters always present, but never spirasters or 

 sterrasters. With trirenes; without calthrops. Chamber-system aphodal, and 

 choanosomal mesoderm sarcenchymatous. Megascleres generally arranged on 

 the radiate type. Myriastra Soil. ; Pilochrota Soil. ; Astrella Soil. ; Anthastra 

 Soil. ; Stelletta 0. Schm. ; Dragmastra Soil. ; Aurora Soil. ; Ancorina O. Schm. ; 

 Tribrachium Weltner; Tethyopsis Stewart; Disyringa Soil.; Stryphnus Soil.; 

 Ecionema Bow.; Papyrula 0. Schm.; Psammastra Soil.; Algol Soil. 



Fam. 4. Geodiidae. The characteristic microsclere is a sterraster. With 

 trisene megascleres. The sterrasters in the cortex are united together by 

 fusiform fibrillated cells. Erylus Gray ; Caminus 0. Schm. ; Pachymatisma 

 Bow. ; Cydonium Fleming ; Geodia Lamarck ; Synops Vos. ; Isops Soil. 



Fam. 5. Placospongidae. The characteristic microsclere is a sterraster. 

 The only megascleres are tylostyles ; triames absent. Often placed with the 

 Suberitidce (Monaxonid) on account of tylostyles. Placospongia Gray. 



Tribe 3. MEGASCLEROPHORA. Without microscleres. 



Fam. Tethyopsillidae. Proteleia K. and D.; Tellnjopsilla Lendf. 



Sub-order 2. LITHISTIDA. 



Tetractinellida provided with a consistent skeleton by the zygosis of modified 

 spicules or desmas. 



Tribe 1. HOPLOPHORA. With special ectosomal spicules, and usually some 

 form of microsclere. 



A. Ectosomal spicules as tricenes. Aphodal. 



Fam. 1. Tetracladidae. Desma tetracremd. Theonella Gray ; Discodermia 

 Bocage ; Racodiscula Zittel ; Kaliapsis Bow Neosiphonia Soil. ; Rimella 

 0. Schm.; Collinella 0. Schm.; Sulcastrella 0. Schm. 



Fam. 2. Corallistidae. Desma monocrepid (i.e., with crepis as monaxon) 

 and tuberculated. Aphodal. Corallistes 0. Schm. ; Macandrewia Gray ; 

 Dccdalopelta Soil. ; Heterophymia Pomel ; Callipelta Soil. 



Fam. 3. Pleromidae. Desma monocrepid and smooth. Aphodal. Pleroma 

 Soil.; Lyidium 0. Schm. 



B. Ectosomal spicules as microstrongyles or modified microstrongyles (discs}. 

 Desmas monocrepid. 



Fam. 4. Neopeltidae. Ectosomal spicules as monocrepid discs. Neopelta 

 0. Schm. 



Fam. 5. Scleritodermidae. Ectosomal spicules as microstrongyles and the 

 other microscleres as sigmaspires. Sderitoderma 0. Schm. ; Aciculites 0. Schm. 



Fam. 6. Cladopeltidae. Ectosomal spicules as a monocrepid desma highly 

 branched in a plane parallel to the surface. Microscleres absent. Siphonidium 

 0. Schm. 



