SXIV 



CONTENTS. 



Sixth Section. BracMopoda. 



Paragraph Page 



238. General review of the gronp 306 



BibHography ........... 307 



239. Form of the body 307 



210. Integument, shell, and arms ........ 308 



241. Jliiscular system . - ■ 309 



242. Nervous system and sensory organs ...... 309 



243. Alimentary canal 310 



244. Coelom and circulatory organs 310 



245. Excretory organs 312 



246. Generative organs 314 



Seventh Section. Mollusca. 



217. General review of the group 315 



Bibliogi-aphy 317 



248—252. Form of the body 318 



253. 254. Appendages 325 



255. 256. Integument 328 



257—259. Shell 329 



260—263. Gills 335 



264. Internal skeleton .......... 341 



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 363 



289—292. Excretory organs ' . . 375 



293-298. Generative organs 380 



Eighth Section. Tunicata. 



299. General review of the group 388 



Bibliography 389 



300. 301. Form of the body 390 



302. Integument 393 



303. Skeleton 394 



304. Muscular system 394 



305. 306. Nervous system 395 



