LIST OF ILLUSTRATIONS. xix 
PAGE 
Nervous system of Spekia zonata, Fig. 41 ..... 258 
Semi-diagram of Spekia, Fig. 42 . . . . . . .259 
Semi-diagram of Spekia, Fig. ^3 ...... 260 
Shells of Neothauma, Fig. 44 . . . . . . .261 
Nervous system of Neothauma, Fig. 45 . . . . . . 263 
Nervous system of Vivipara, Fig. 46 . . . . . .264 
CHAPTER XL 
Diagram of molluscs . . . . . . . . -273 
Diagram of molluscs . . . . . . . . - 275 
CHAPTER XII 
Limnothelphusa maculata, Fig. 1 . . . . . .281 
Platythelphusa armata. Fig. 2 . . . . . . .285 
Limnocaridina tanganyikice, Fig. 3 . . . . . . .287 
Palaemon moorei , Fig. 4. . . . . . . .293 
CHAPTER XIII. 
Arachnoidiae ray lankesteri ........ 296 
CHAPTER XIV. 
Living Tanganyika medusa ........ 299 
„ „ „ , another 301 
Semi-diagram of medusa buds ........ 303 
Young bud 305 
„ , rather older ......... 306 
„ , still older ......... 307 
CHAPTER XV. 
Spotigella moorei . . . . . . . . . .311 
Skeleton of Spongella moorei . . . . . . . .313 
Spongella tanganyikce . . . . . . . . .319 
Potamolepis veltneri . . . . . . . . . 323 
CHAPTER XVII. 
Pyrgulifera humerosa . . . . . . . . 343 
Paramelania and pur purina . . . . . . • 345 
Nassopsis and purpurina. . . . . . . . *34 7 
