PLATE IX. 



IsoDiCTYA soiTULA, Bowerbanh. 



Figs. 1, 2 and 3. — Specimens of the sponge growing 

 on Nullipara polymorpJka. Natural size. 



For figures of the spicula of this sponge see 

 Plate lY, figs. 1—3. 



IsoDiOTTA PERPLEXA, Bowerhanh. 



Figs. 4 and 5. — Represent the type specimens of the 

 sponge coating Nullipora polymorpha of the natural 

 size. 



Fig. 6. — A portion of the dermal membrane. 



Fig. 7. — One of the long fusiformi-acerate spicules 

 of the skeleton. 



