PLATE X. 



ISODICTYA INVOLUTA, Bowerbank. 



Fig. 1. The type growing on Nullipora polymorplia. 

 From Westport Bay. In the collection of the Rev. 

 A. M. Norman. 



Fig. 2. A portion of the dermal membrane. 



Fig. 3. One of the slender, acuate, tension spicula. 



Fig. 4. One of the stout acuate spicula of the 

 skeleton. 



ISODICTYA PAUPERCULA, Bowerlank. 



Fig. 5. The type on the inside of a valve of Pecten 

 varius. From Birterbuy Bay. In the cabinet of 

 the Rev. A. M. Norman. 



Fig. 6. A portion of the sparingly spiculous dermal 

 membrane. 



Fig. 7. Very slender acerate spicule of the dermal 

 membrane. 



Fig. 8. One of the stout acerate spicula of the 

 skeleton. 



[Fig. 9. This Plate was engraved before Dr. Bower- 

 bank's death, but not lettered ; nor was any descrip- 

 tion of it to be found among the author's papers. 

 The bidentate equi-anchorate spicula (Fig. 9) is of 

 very unusual form, but no such spicule is referred to 

 in the descriptions of the two sponges which are 

 illustrated in this Plate.] 



