OF THE SPONGIAD7K. 275 



FIG. 



283. Detached nucleated cells, from a new species of 



sponge, from Freemantle, Western Australia. 

 X 308 linear. 



284. A view of the upper stratum of cells in one of the Ovaria 



of SpongiUa Carteri, Bowerbank. X 308 linear. 

 For cellular tissue in Grantia see Figs. 312 and 

 314, Plate XXI, Pages 82 and 139. 



SARCODE. 



285. Represents a small piece of an interstitial membrane 



from the honeycomb sponge of commerce in the 

 condition in which it came from the sea, exhibiting 

 the sarcode in situ and the imbedded semi-digested 

 molecules of nutriment. X 660 linear. Page 88. 



INTERNAL AND EXTERNAL DEFENCES. 



286. A small portion of a longitudinal section through the 



cloaca of a specimen of Grantia tessellata, Bower- 

 bank, MS., showing the positions of the internal 

 defensive spicula, and their curvature towards the 

 mouth of the cloaca. X 108 linear. Page 29. 



287. A portion of a thin section at right angles to the surface 



of a specimen of Chalina seriata, Bowerbank, illus- 

 trating the mode of external defence by the pro- 

 longation of the radial lines of the skeleton. X 108 

 linear. Page 24. 



288. A small portion of the kerato-fibrous skeleton of an 



i 



Australian sponge, showing the attenuato-acuate 

 entirely spined internal defensive spicula in situ 

 dispersed on the skeleton fibre. X 108 linear. 

 Page 31. 



289. Verticillately spined internal defensive spicula dis- 



persed on keratose fibres of the skeleton, from a 

 West Indian sponge. X 175 linear. Pages 23 

 and 125. 



