PLATE XII. 

 IsoDiCTTA HISPIDA, Bowerbank. 



Figs. 1 and 2. — The typical specimens on NulUpora 

 jaolymorpha. In the Rev. A. M. Norman's collection. 

 Natural size. 



Fig. 3. — A section of the dermis at right angles to 

 the surface. 



Fig. 4. — A slender, acuate, tension spicule. 



Fig. 6. — Two of the bidentate, equi-anchorate, 

 retentive spicula. 



IsoDiOTYA NODOSA, BowerbanJc. 



Fig. 6. — The type from Birterbuy Bay. In the 

 cabinet of the Rev. A. M. Norman. Natural size. 



Fig. 7. — One of the subfusiformi acuate spicula of 

 the skeleton. 



