118 PLATE XLVI. 



tive spiculum, from the interstitial membranes. X 530 

 linear. 



Fig. 29. One of the small series of bidentate, equi- 

 ancliorate, retentive spicula, of the interstitial mem- 

 branes. X 530 linear. 



The great comparative size of the spicula of this 

 little sponge is very characteristic of the species. 



