12 A MONOGRAPH OP THE 



Suborder VII. Canaliculated siliceo-fibrous reticulated 

 skeletons. Fibres composed of concentric layers of 

 solid silex, with a continuous central canal. Reticu- 

 lations symmetrical. 



Paerea, Bowerhank. 



Skeleton siliceo-fibrous. Fibres cylindrical, canaliculated. 

 Reticulatiotis symmetrical, rectangular. Vol. I, p. 204. 



Type, Farrea occa, Bowerbank, MS. Vol. I, Plate XVI, 

 Fig. 277. 



Order III.— KERATOSA. 



Suborder I. Solid non-spiculate kerato-fibrous skeletons. 



1. Spongia, Linnaeus. 



2. Spongionella, Bowerbank. 



1. Spongia, Linnosus. 



Skeleton kerato-fibrous. Fibre solid, cylindrical, aspiculous. 

 Rete unsymmetrical. Vol. I, p. 205. 



Type, Spongia officinalis, Linnaeus. Vol. I, Plate XIII, 

 Fig. 261, and Plate XXXVIL Fig. 379. 



2. Spongionella, Bowerhank. 



Spongia, Sowerhy and Johnston. 



Skeleton kerato-fibrous. Fibres solid, cylindrical, aspiculous. 

 Rete symmetrical ; primary fibres radiating from the 

 base to the apex. Secondary fibres disposed at nearly 

 right angles to the primary ones. Vol. I, p. 206. 



