CONTENTS. XIX 



PAGE 



Elongate Spicula . . 262 



Birotulate and Boletiform Spicula . 264 



New forms of Spicula . . . 267 



Spicula the position of which is unknown . 269 

 Membranous Tissues . . .271 



Fibrous Structures .... 272 



Keratose Fibrous Tissue . 272 



Prehensile Fibre .... 274 



Fibrilated . 274 



Cellular Tissue . . . 274 



Sarcode . . . . 275 



Internal and External Defences . . 275 



Intermarginal Cavities . . . 277 



Cilia and Ciliary Action . . . 279 



Eeproductive Organs . . . 279 



ILLUSTBATIONS or THE GENERA . . . 283 



Order 1. CALCAEEA ... . 283 



Grantia, Leucosolenia, Leuconia, Leucogypsia . 283 



Order 2. SILICEA . . . 284 



Suborder 1 . . 284 



Geodia, Pachymatisma, Ecionemia, Alcyoncellum . 284 

 Polymastia, Halyphysema, Ciocalypta, Tethea, 



Halicnemia . . . 285 

 Dictyocylindrus, Phakellia, Microciona, Hyme- 



raphia . . . 286 



Hymedesmia .... 287 



Suborder 2 . . .287 



Hymeniacidon . . . 287 



Suborder 3 . . .287 



Halichondria, Hyalouema, Isodictya, Spongilla . 287 



