124 PLATE XLV11I. 



Fig. 12. A skeleton spiculuin. X 250 linear. 

 Fig. 13. One of the dermal tension spicula. X 250 

 linear. 



ISODICTYA VAEIANS, Bowerbank. 



Vol. ii, p. 281, ' Mon. Brit. Spongiadse.' 



Fig 14. Represents the type-specimen of the 

 species in the Johnstonian collection in the British 

 Museum, marked 17 e , and labelled Halichondria cinerea. 

 Natural size. 



Fig. 15. A skeleton spiculum. X 250 linear. 



Fig. 16. One of the short, stout, acuate spicula. 

 X 250 linear. 



