BRITISH SPONGIAD'^E. 15 



differ in size, form, and mode of arrangement, to so great 

 an extent as to afford the means of very satisfactory specific 

 descriptions. 



Suborder IV. Simple fistulo-fibrons skeletons. Cavity of 

 the fibre simple, central, and continuous. 



Verongia, Boiverbank. 



SponTha fistulosa, Lamarck. 



Skeleton kerato-fibrous. Fibres cylindrical, continuously 

 fistulose, aspiculous. Rete unsymmetrical. Vol. I, 

 p. 209. 



Type, Verongia fistulosa {Spongia fistulosa, Lamarck). 

 Vol. I, Plate XIII, Fig. 266. 



Suborder V. Compound fistulo-fibrous skeletons. Central 

 cavity of the fibre single and continuous, having 

 secondary caecoid branches radiating from it at nearly 

 right angles. 



Auliskia, Bower bank. 



Skeleton kerato-fibrous. Fibres aspiculous, cylindrical, 

 continuously fistulose, primary fistulas having minute 

 csecoid canals radiating from them in every direction. 

 Rete unsymmetrical. Vol. I, p. 210. 



Type, a fragment of the skeleton in the cabinet of the 

 author. Vol. I, Plate XIV, Fig. 268, and Plate XIII, 

 Fig. 267. 



Suborder VI. Regular semi-areno-fibrous skeletons. 

 Skeleton regular areno-fibrous, having a well-defined 



