BRITISH SPONGIAD^. 



Order II.— SILICEA. 



Suborder I. Spiculo-radiate skeletons. Not reticulate. 

 Composed of spicula radiating in fasciculi or sepa- 

 rately from the base or axis of the sponge. 



1. Geodia, Lamarck. 9. Halienemia, Bower- 



2. Tachymatisma, Bower- bank. 



bank. 10. Bictyocylindrus, Bower- 



3. Ecionemia, Bowerbank^ bank. 



' 4. Alcyoncellufn, Quoy et 11. Phakellia, BowerbanL 

 Gaimard. 12. Microciona,^ovie,xhaak. 



5. Polymastiay'Qo'werhavik. 13. Hymeraphia, Bower- 



6. Halyphysema, Bower- bank. 



bank. 14. Hymedesmia, Bower- 



7. Ciocalypta, Bowerbank. bank. 



8. Tethea, Lamarck. 



1. Geodia, Lamarck. 



Skeleton. Spicula fasciculated, radiating from the base or 

 central axis of the sponge to the surface. Dermis 

 crustular, furnished abundantly with closely packed 

 ovaria. Ovaria siliceous, composed of cuneiform 

 spicula,- firmly cemented together by silex, in lines 

 radiating from the centre of the ovary. Pores fur- 

 nished with oesophageal tubes, terminating in the 

 distal extremity of the intermarginal cavities. Inter- 

 marginal cavities separate, symmetrical, subcylindrical ; 

 each furnished with a membranous valve at its proxi- 

 mal extremity. Vol. I, p. 167. 



Type, Geodia Barretti, Bowerbank, MS. Vol. I, Plate 

 XXVIII, Fig. 354, and Plate XIX, Pigs. 301, 302. 



2. Pachymatisma, Bowerbank. 



Skeleton composed near the external surface occasionally of 



