PLATE XII. 



ISODICTYA HISPIDA, BowerbanJc. 



Figs. 1 and 2.- -The typical specimens on Nullipora 

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

 Natural size. 



Fig. 3. A section of the dermis at rio-ht angles to 



CD <~J CJ 



the surface. 



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



Fig. 5. Two of the bidentate, equi-anchorate, 

 retentive spicula. 



ISODICTYA 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. 



