62 



COELENTEEATA— PORIFEEA 



PHYLUM II 



Genera incertae sedis. 



Pattersonia Miller {Strohilospongia Beecher). In form of large botryoidal 

 clumps. Brachiospongia Marsh. Vase-like sponges Avith broad inferior margin 

 prolonged into a number of hollow arms. Ordovician of North America. 

 These, together with Amphispongia Salter, and Astroconia Sollas, from the 

 Silurian of England, represent extinct families of the Lyssacina. 



Fyriionema M'Coy (Acestra Eoem.) Fascicles of long, stout spicules, 

 supposed to be root-tufts. Silurian, 



Hyalostelia Zitt. (Acanthospongia Young). Skeletal elements relatively large, 

 in the form of regular hexactins and stellate bodies with reduced vertical ray, 

 and with inflated nodes. 

 Root-tuft composed of elon- 

 gated, slightly bent fibres, 

 sometimes terminating in 

 four recurved rays. Cam- 

 brian to Lower Carboni- 

 ferous ; Great Britain. 



Holasterella Carter; 

 Spiradinella (Fig. 65), and 

 Acanthactinella Hinde, are 

 allied genera occurring in 

 the Lower Carboniferous 

 of Great Britain. 



ThoUasterella Hinde (Fig. 



Fio. 66. 



Thnliastcrella gracilis 

 Hinde. Carboniferous 

 Limestone ; Dairy, Ayr- 

 shire. Dermal layer with 

 fused stellate spicules, 

 5/i (after Hinde). 



■ S^^SB^^^^ 



Fig. 65 



Spiractinella wriciMil (Carter). 

 Carboniferous Limestone ; Sligo, 

 Ireland. A, Normal hexactin. B, 

 Hexactin with forked rays, 5/j 

 (after Hinde). 





Fig. 67. 



AsteractineUa expansa Hinde. 

 Carboniferous Limestone ; 

 Dairy, Ayrshire. Skeletal 

 element, 5/j (after Hinde). 



Fig. 68. 



Astraeospongia meniscus Roemer. 

 Silurian ; Tennessee. A, Sponge, in 

 profile, 2/3 natural size. B, IJpper 

 surface of same. 



66), from the Carboniferous, has thin walls composed of a layer of robust, 

 irregularly amalgamated hexactins. As a rule, two of the rays lying in the 

 same plane divide dichotomously from the nodes outward, so as to produce 

 a six-armed instead of a four-armed cross. In AsteractineUa Hinde (Fig. 67), 

 all of the rays lying in the same plane divide in two or more branches, thus 

 giving rise to many-rayed, extremely diverse, stellate and corolla-like bodies. 

 Carboniferous ; Ayrshire. 



Astraeospongia Roem. (Fig. 68). Thick-walled, depressed, bowl-shaped, 

 upper surface concave, lower convex, without traces of attachment. Skeleton 

 composed of relatively' large, homogeneous, uncemented cruciform spicules ; 

 six of the rays are disposed in the same plane, while the two rays projected 

 at right angles to these are reduced to short, button-like prominences. Common 

 in Silurian of Tennessee and Devonian of the Eifel. 



