SPONGES 123 



Family 5. IHyaloxematidae, Gray (Scbulze, 1893). Pentactinal 

 pinuli in both dermal and gastral membranes. (o) Sub-Family 1. 

 IHyalonematixae, F.E.S. Genera — j Hyalonema, Gray [Eoc], (Fig. 19) ; 

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

 M'Coy [Sil.] ; *Oiicosella, Rtf. [Sil.]. (6) Sub-Family 2. Sempeuellinak, 

 F.E.S. Genus — Semperella, Gray. 



To these must be added the following families of extinct Lyssaciua : — 

 Family 6. *Protospongidae, Hinde (Rauff. 1893). Genera — Protosponyia, 

 Salter [Cambr.] ; Phormosella, Iliiule [Sil.]. Family 7. *Dictyospon- 

 GiDAE, Eft". Genus — Didijophyton, Hall [Sil. Dev.]. Family 8. *Plecto- 

 spoxgiadae, Rff. Genera — Cyathophycus, AYalc. [Sil.] ; PalaeosaccuK, 

 Hinde [Ordov.] ; Acanthodictya, Hinde [Sil.] ; Pledoderma, Hinde [Sil.]. 

 Family 9. *Brachiospongidae, Beecher. Genus — Brachiosjwngia, Marsh 

 [Sil.]. Family 10. "^Pattersoxidae, Rff. Genus — Pattersonia, S. A. 

 Miller [Sil.]. Family 11. ^Reckptaculitidae, Eichw. Genera — Ischadites, 

 Murch. [Ordov. Sil.] ; Sphaerospongia, Peng. [Dev.] ; Eecej^taaditcs, Defr. 

 [Ordov. Sil. Dev. Carb.]. Family 12. *Amphispoxgidae, Rif. Genus 

 — Arnj^hupongia, Salter [Sil.]. Family 13. *Moxakidae, Marshall. 

 Genus — Stauradinella, Z. [Cret.]. Family 14. *Pollakidae, Marshall. 

 Genera — Hyalostelia, Z. [Carb. Cret.] ; Holasterella, Crtr. [Carb.] ; S2nr- 

 adinella, Hinde [Carb.] ; Acanthadinella, Hinde [Carb.]. 



Incerti sedis — *Astroconia, Soil. [Sil.] ; *Teganium, 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-Cl.\SS 2. DiCTVOXIXA, Z. 



The large parenchymal hexactines are from the first united more or 

 less regularly as didyonalia into a firm framework. 



Order 1. Uncinataria, F.E.S. 

 With uncinates. 



Sub-Order 1. Clavularia, F.E.S. 



Groups of radially disposed davulae in addition to pentactinal hypo- 

 dermalia and hypogastralia, sometimes also scopuhie. 



Family 1. Farreidae, F.E.S. In the youngest portions of the tubes 

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

 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. 



Sub-Order 2. Scopularia, F.E.S. 



Groups of radially disposed scapulae in addition to pentactinal hypo- 

 dermalia and hypogastralia, never with chnmlae. 



* 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 wliole family is known only iuthe fossil condition, 

 the asterisk is not aflixed to eacli separate genus. 



