328 A MONOGRAPH OF THE 



The central canals, and the concentric layers of silex in the 

 radii, are remarkably distinctly exhibited. 



I am indebted to my friend. Dr. Battersby, for the first 

 intimation I received of the existence of this curions and 

 interesting species on our own coasts ; he found it at 

 Torquay, at extreme low- water mark, on the rocks of Abbey 

 Bay, adjoining Torquay. Preserved in salt and water, it is 

 almost as solid as a piece of boiled bullock's liver. 



This sponge varies so widely from the ordinary structures 

 of Hymeniacidon, that I doubt much whether it should not 

 have been made the type of a new genus. 



Halichondria, Fleminff. 



Section * Skeleton spicula, acerate. 



1. Halichondria panicea, Johnston. 



2. — (j/labra, Bowerbank. 



3. — angulaia, Bowerbank. 



4. — cadttca, Bowerbank. 



5. — inconspicua, Bowerbank. 



6. — incerta, Bowerbank. 



7. — coalita, Johnston. 



8. — distorta, Bowerbank. 



Section * * Skeleton spicula, acuate. 



Sub-seetion A. Skeleton spicula, smooth. 



9. Halichondria corrugata, Bowerbank. 



10. — Thompsoni, Bowerbank. 



11. — forcipis,'Q(m%rh&-Qk. 



12. — simplew,'Qovfe.xh?ivik. 



13. — subdola, Bowerbank. 



