SPONGES 123 



FAMILY 5. IHYALONEMATIDAE, Gray (Schulze, 1893). Pentactinal 

 pinuli in both dermal and gastral membranes. (a) SUB-FAMILY 1. 

 IHYALOXEMATINAE, F.E.S. Genera jHyalonema, Gray [Eoc.], (Fig. 19) ; 

 jPheronema, Leidy [Eoc.] ; Poliopogon, W. Th. (Fig. 20, B) ; * Pyritonema, 

 M'Coy [Sil.] ; *0ncosella, Rff. [Sil.]. (6) SUB-FAMILY 2. SEMPERELLINAK, 

 F.E.S. Genus Semperella, Gray. 



To these must be added the following families of extinct Lyssacina : 

 FAMILY 6. *PROTOSPONGIDAE, Hinde (Rauff. 1893). Genera Protospongia, 

 Salter [Cambr.] ; Phormosella, Hinde [Sil.]. FAMILY 7. *DICTYOSPON- 

 GIDAE, Rff. Genus Dictyophyton, Hall [Sil. Dev.]. FAMILY 8. *PLECTO- 

 SPONGIADAE, Ktf. Genera Oyathophycus, Wale. [Sil.] ; Palaeosaccus, 

 Hinde [Ordov.] ; Acanthodidya, Hinde [Sil.] ; Plectoderma, Hinde [Sil.]. 

 FAMILY 9. *BRACHIOSPONGIDAE, Beecher. Genus Brachiospongia, Marsh 

 [Sil.]. FAMILY 10. *PATTERSONIDAE, Rff. Genus Pattersonia, S. A. 

 Miller [Sil.]. FAMILY 11. *RECEPTACULITIDAE, Eichw. Genera Ischadites, 

 Murch. [Ordov. Sil.] ; Sphaerospongia, Peng. [Dev.] ; Receptaculites, Defr. 

 [Ordov. Sil. Dev. Carb.]. FAMILY 12. *AMPHISPONGIDAE, Rff. Genus 

 Amphispongia, Salter [Sil.]. FAMILY 1 3. *MONAKIDAE, Marshall. 

 Genus Stauractinella, Z. [Cret.]. FAMILY 14. *POLLAKIDAE, Marshall. 

 Genera Hyalostelia, Z. [Carb. Cret.] ; Holasterella, Crtr. [Carb.] ; Spir- 

 actimlla, Hinde [Carb.] ; Acantlwictinella, Hinde [Carb.]. 



Incerti sedis * Astroconia, Soil. [Sil.] ; *Teyanium, Rff. [Sil.]. 



(Note. Families 13 and 14 represent two groups, which, so far as 

 living forms are concerned, have been broken up and distributed amongst 

 other families, and it only remains for the fossil forms to be similarly 

 treated.) 



SUB-CLASS 2. DICTYONINA, Z. 



The large parenchymal hexactines are from the first united more or 

 less regularly as dictyonalia into a firm framework. 



ORDER 1. Uncinataria, F.E.S. 

 With uncinates. 



SUB-ORDER 1. CLAVULARIA, F.E.S. 



Groups of radially disposed clavulae in addition to pentactinal hypo- 

 dermalia and hypogastralia, sometimes also scopulae. 



FAMILY 1. FARREIDAE, F.E.S. In the youngest portions of the tubes 

 the dictyonal framework consists solely of a single-layered network with 

 square meshes, each node of intersection bearing on either side a conical 

 boss projecting at right angles. Genera Farrea, Bwk. (Fig. 21) ; Clavis- 

 copulia, F.E.S. 



SCB-ORDER 2. SCOPULARIA, F.E.S. 



Groups of radially disposed scopulae in addition to pentactinal hypo- 

 dermalia and hypogastralia, never with clavulae. 



* Fossil forms : Cambr. = Cambrian ; Ordov. = Ordovician ; Sil. = Silurian ; Dev. = 

 Devonian; Carb. = Carboniferous ; Eoc. = Eocene; other references as under Calcarea 

 (above, footnote to p. Ill) : if the whole family is known only in the fossil condition, 

 the asterisk is not affixed to each separate genus. 



