124 SPONGES 



FAMILY 2. f EURETIDAE (Z.), F.E.S. Branched anastomosing tubes, form- 

 ing an irregular framework or the wall of a cup ; dictyonal framework of 

 the tubular wall always several layers, never, as in Farrea, a single-layered 

 network. Genera Eurete, Crtr. ; Periphragella, Marshall ; Lefroyella, W. 

 Th. ; *Tremadictyon, Z. [Jur.] ; *Craticularia, Z. [Jur. Cret.] ; *Sphenaulax, 

 Z. [Jur.]; *Sporadopyle, Z. [Jur.] ; * Verrucocoelia, Et. [Jur.] ; *Stauronema, 

 Soil. [Cret.] ; * 'Sestrodictyon, Hinde [Cret.] ; * Calathiscus, Soil. [Ool.]. 

 FAMILY 3. IMELLITTIONIDAE, Z. Body in the form of a system of ramified 

 tubes or of a cup with lateral diverticula ; dictyonal framework with 

 irregular meshes ; parietal skeleton honeycomb -like, with more or less 

 hexagonal canals disposed radially ; each such canal occupied by an 

 extension of the chamber layer, and covered over externally by the 

 dermal, internally by the gastral membrane. No scopulae in gastral 

 skeleton. Genus f A phroca llistes, Gray [Cret. Eoc.], (Fig. 22). FAMILY 4. 

 ICosciNOPORiDAE, Z. Body cup-shaped or plate-like, the wall traversed 

 by elongated, funnel-shaped, straight canals (incurrent and excurrent), 

 of which the wide openings, covered by the sieve-like limiting membrane, 

 are placed alternately on either surface of the wall, while the other 

 extremity ends in a blind point. Genera *Coscinopora, Goldf. [Cret.] ; 

 *Leptophragma, Z. [Cret.] ; *Pleurostoma, Roem. [Cret.] ; *Guettardia, Mich. 

 [Cret] ; Chonelasma, F.E.S. ; Bathyxiphiis, F.E.S. FAMILY 5. TRE- 

 TODICTYIDAE, F.E.S. Incurrent and excurrent canals penetrate the body 

 wall with an oblique, longitudinal, or even curved course, not trans- 

 versely. Genera Hexactinella, Crtr.; Cyrtaulon, F.E.S. ; Fieldinyia, 

 Sav. Kent. ; Sclerothamnus, Marshall. 



ORDER 2. Inermia, F.E.S. 



Without uncinates or scopulae. 



FAMILY 6. JMAEANDROSPONGIDAE, Z. The body consists of a con- 

 nected system of labyrinthine anastomosing tubes, between which there 

 is a connected interstitial system of interspaces. The water entering 

 by the latter passes through the walls of the tubes and along them 

 either into the gastral cavity or directly to the exterior. Genera 

 Dactylocalyx, Stutchb. ; Margaritella, O.S. ; Scleroplegma, O.S. ; Myliusia, 

 Gray ; Aulocystis, F.E.S. ; *Plocoscyphia, Rss. [Cret.] ; * Etheridgia, Tate 

 [Cret] ; *Toulminia, Z. [Cret.] ; *Camerospongia, d'Orb. [Cret] ; *Cysti- 

 spongia, Roem. [Cret.]. 



To these must be added the following extinct families : FAMILY 7. 

 *STAURODERMIDAE, Z. (with sub-families POROSPONGINAE and STAURO- 

 DERMINAE, Rff.). Genera Cypellia, Pom. [Jur.] ; Stauroderma, Z. [Jur.] ; 

 Purisiphonia, Bwk. [Jur. Cret.] ; Porocypellia, Pom. [Jur.] ; Casearia, 

 Qst. [Jur.] ; Porospongia, d'Orb. [Jur.] ; Ophrystoma, Z. [Cret.] ; Cincli- 

 derma, Hinde [Cret] ; Eubrochiis, Soil. [Cret] ; Placotrema, Hinde 

 [Cret]. FAMILY 8. *CALLODICTYOXIDAE, Z. Genera Callodictyon, Z. 

 [Cret.] ; Marshallia, Z. [Cret.] ; Porochonia, Hinde [Cret.] ; Becksia, Schliit. 

 [Cret.] ; Pleurope, Z. [Cret] ; Diplodictyum, Z. [Cret.] ; Sclerokalia, Hinde 

 [Cret.]. FAMILY 9. *COELOPTYCHIDAE, Z. Genus Coeloptychium, Goldf. 



