XVlU CONTENTS. 



PAGB 



Order 3. Keeatosa . . . ■ • 205 



SpoDgia . . . ■ • "05 



Spongionella . . . • ■ 206 



Halispongia .... 207 



Chalina . . . . 208 



Verongia. . . . • 209 



AulisMa . . . . . 210 



Stematumenia .... 211 



Ow THE DiSCHIMINATION OF THE SPECIES OF THE SpONGIAD^ 212 



The Spicula 



The Oscula 



The Pores 



The Dermal Membrane . 



The Skeleton 



The Interstitial Membranes 



The Intermarginal Cavities 



The Interstitial Canals and Cavities 



The Cloacal Cavities 



TheSarcode . 



The Ovaria and Gemmules 



. 213 



. 215 



. 216 



. 216 



. 217 



. 218 



. 218 



. 219 



. 219 



. 220 



. 221 



On the Peeseetation oe the SpoNaiADJs . . . 225 



Teeminolo&t, and Debceiptions oe the Illtjsteatite 



FiGTJEES . . . . , . 228 



Spicula of the Skeleton . . . . 229 



Connecting Spicula . . . 234 



Prehensile Spicula . . , . 287 



Defensive Spicula .... 237 



Spicula of the Membranes . . . 243 



Tension Spicula • • . . 243 



Eetentive Spicula . . . . £46 



Compound Stellate Spicula . . . 257 



Spicula of Ovaries and G-cmmules . . 262 



