SPONQIDA. 
10 Spong, 
Polyhlastidium. Polyzoic ; perforated octahedral nodes ; veil ; no 
radial canals ; isolated rod-like spicules (p. 52). 
Stauroderma. Polyzoic; ostia on outer wall; skeleton irregular; 
veil (p. 63). 
Ophryatoma. As Porospongia, D’Orb., but veil with axial crosses only, 
and nodes perforated (p. 66). 
Tremabolites. Of anastomosing tubes or leaves ; veil superior ; octa- 
hedral nodes (p. 55). 
Toulminia. Of thick meandric laminae ; root branched ; veil as pre- 
ceding (p. 66). 
Callodictyon. Wall even ; rectangular spined meshes ; nodes per- 
forated; no canals (p. 57). 
Marshallia. As preceding ; but walls folded, with apertures (p. 58). 
Pleurope. Lateral apertures ; bundles of fibres form base, and run 
over the rectangular meshes ; nodes perforate (p. 68). 
Diplodictyon. Broad, with round apertures; canals in outer layer 
only ; outer layer with solid nodes ; inner, with lantern-nodes (p. 59). 
Stauractinella. Spherical ; skeleton of isolated 6-radiates ; nodes and 
arms hardly thickened anywhere (p. 60), 
