xxiv 



CONTENTS. 



Sixth Section. Brachiopoda. 



Tape 

 306 



307 



307 



308 



309 



309 



310 



310 



312 



314 



Seventh Section. Mollusca. 



247. General review of the group 315 



Bibliography ........... 317 



248—252. Form of the body 318 



253. 254. Appendages 325 



255. 256. Integument 328 



257—259. Shell 329 



2C0— 2G3. Gills 335 



264. Internal skeleton 311 



265. Muscular system 342 



266—269. Nervous system 343 



Central organs and nerves of the body ..... 343 



- 270. Visceral nerves .^351 



271. Sensory organs : 351 



Tactile and olfactory organs ....... 351 



272. 273. Visual organs 353 



274. Auditory organs . 356 



275 — 279. Alimentary canal 358 



280. Organs appended to the alimentary canal ..... 363 



1) Appendages of the fore-gut 363 



281. 2) Appendages of the mid-gut 364 



282. 3) Appendages of the hind-gut 366 



283. Coelom 367 



284—288. Vascular system 368 



289—292. Excretory organs 375 



293—298. Generative organs 380 



Eighth Section. Tuilicata. 



299. General review of the group ........ 388 



Bibliography 389 



300. 301 . Form of the body 390 



302. Integument 393 



303. Skeleton 394 



301. Muscular system 394 



305. 306. Nervous system 395 



