XV111 CONTENTS. 



PAGE 



Order 3. KERATOSA . . . . 205 



Spongia ..... 205 



Spongionella . . . . 200 



Halispongia . . . 207 



Chalina . ... 208 



Verongia ..... 209 



Auliskia . . . 210 



Stematumenia .... 211 



ON THE DISCRIMINATION or THE SPECIES OF THE SPONGIAD^; 212 



The Spicula . .213 



The Oscula . . 215 



The Pores . 216 



The Dermal Membrane . . 216 



The Skeleton . . 217 



The Interstitial Membranes . .218 



The Intermarginal Cavities . . 218 



The Interstitial Canals and Cavities . .219 



The Cloacal Cavities . .219 



The Barcode . . . 220 



The Ovaria and Gemmules . . .221 



ON THE PRESERVATION OF THE SpONGIAD^ . . . 225 



TERMINOLOGY, AND DESCRIPTIONS OF THE ILLUSTRATIVE 



FIGURES . . 228 



Spicula of the Skeleton . . .229 



Connecting Spicula . . . 234 



Prehensile Spicula . . 237 



Defensive Spicula . . 237 



Spicula of the Membranes . . 243 



Tension Spicula . . . 243 



Retentive Spicula . . . . 246 



Compound Stellate Spicula . . . 257 



Spicula of Ovaries and Gemmules . 262 



