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PLATE LXXXV. 



ISODICTYA FILAMENTA, BowerbanJc. 



Fig. 1. Represents the sponge, mounted in Canada 

 balsam. Natural size. 



Fig. 2. A portion of the sponge at about (a figure 

 1) X 80 linear. 



Fig. 3. One of the slender acerate spicula from the 

 dermal membrane. X 250 linear. 



Fig. 4. An average-sized skeleton spiculum. 

 X 2-50 linear. 



ISODICTYA LUTEOSA, Bowerbank. 



Fig. 5. Represents the type-specimen of the species. 

 Natural size. 



Fig. 6. One of the skeleton spicula. X 250 

 linear. 



Fig. 7. A tension spiculum from the interstitial 

 membrane. X 250 linear. 



ISODICTYA INVALIDA, Bowerbarik. 



Fig. 8. Represents the type-specimen. Natural 

 size. 



Fig. 9. An average-sized skeleton spiculum. X 250 

 linear. These spicula vary considerably in their 

 length. 



Fig. 10. An acerate spiculum from the skeleton, 

 X 250 linear. This form of spiculum occurs very 

 rarely among the normal acuate ones. 



