BRITISH SPONGIADiE. 7 



defensive spicula radiate at right angles to the axial 

 column. Vol. I, p. 185. 



Type, Bictyocylindrus Mspidus, Bowerbank. Vol. I, Plate 



XXXII, Fig. 365, and Plate XXXIII, Pig. 366. 



11. Phakellia, Bowerhanh. 



Skeleton. Composed of a multitude of primary cylindrical 

 axes, radiating from a common base and ramifying 

 continuously, from which emanate at about right 

 angles to the axes a secondary series of ramuli, which 

 ramify continuously as they progress towards the 

 surface, but never appear to anastomose. Vol. 1, 

 p. 186. 



Type, Phakellia ventilabrum, Bowerbank. Vol. I, Plate 



XXXIII, Fig. 367. 



12. Mtcrociona, Bowerbank. 



Skeleton. A common basal membrane, whence spring at 

 or about right angles to its plane numerous separate 

 columns of spicula intermixed with keratode, furnished 

 externally with spicula which radiate from the columns 

 at various angles towards the dermal surface of the 

 sponge. Vol. I, p. 188. 



Type, Mtcrociona atrasanguinea', Bowerbank. Vol. I, 

 Plate XXXIII, Fig. 368, and Plate XXXIV, Fig. 

 369. 



13. Htmeraphia, Bowerbank. 



Skeleton. A single basal membrane, whence spring 

 numerous large separate spicula, which pass through 

 the entire thickness of the sarcodous stratum to or 

 beyond the dermal surface of the sponge. Vol. I, 

 p. 189. 



