54 PLATE XXI. 



Figs. 8, 9. — Acuate spicula from the axis of the 

 sponge. The larger ones (fig. 8) usually form the 

 external defenses, while the smaller (fig. 9) more 

 especially appertain to the skeleton ; but both forms 

 occur intermixed in the axial column. X 80 linear. 



Fio-. 10. — One of the fusiformi-acerate, tension 

 spicula of the interstitial membranes. X 80 Unear. 



Fig. 11. — One of the internal defensive spicula. 

 X 80 linear. 



Fig. 12. — An internal defensive spiculum. X 250 

 linear, to exhibit their exceedingly minute spination. 



Since the description of this species in vol. ii, p. 109, 

 ' Mon. Brit. Spongiada^,' I have received a specimen 

 from Newcastle from Mr. A. Hancock, and another 

 from the coast of Northumberland by the Rev. A. M. 

 Norman, in 1865. Both these specunens were in the 

 dried state, and were very similar in their external 

 characters to the specimens I received from Mr. Bean. 

 Mr. W. Saville Kent dredged two specimens off Guern- 

 sey in 1870, and preserved them in spirit in the state 

 in which they came from the sea. The colour in this 

 condition was a dull olive green. The largest of the 

 two did not exceed eight lines in height; they were 

 irregularly cylindrical, and about two lines in diameter. 

 Their surfaces were very hirsute, the external defensive 

 spicula projecting beyond the dermal surface for a half 

 or two thirds of their leno-th. 



Phakellia eobusta, Bou-erhank. 



Vol. ii, p. 120, ' Mon. Brit. SpongiaJjc.' 



Fig. 13. — A specimen of the sponge in the wet 

 condition. Natural size. 



This is not the type-specimen described in vol. ii, 

 p. 120, but another one that I subsequently received, 

 with many others of the same species, from my friend 

 Mr. Peach. They are all very nearly of the same size. 

 The one figured was selected in conse(iucnce of its fine 



