LIST OF ILLUSTRATIONS. Xxi 



PAGE 



230. Spicules of Alcyonium and Gorgonia, ..... 472 



231. Ditto of Gorgonia guttata, . . . . . 472 



232. Spicules of Muricea elongata, ...... 472 



233. Filiferous capsules of Actinia, &c., after Gosse, . . . 475 



234. Section of Shell of Echinus, . . . , . .478 



235. Calcareous reticulation of Spine of Echinus, . . . 478 



236. Ambulacral disk of Echinus, ...... 478 



237. Transverse Section of Spine of Acrodadia, . . . . 479 



238. Spines of Spatangus, . . . . . . .481 



239. Calcareous skeleton of Astrophyton, .... 482 



240. Ditto of Holothuria, . . . . .485 



241. Ditto of Synapta, . . . . . 486 



242. Ditto of Chirodota, . . . . .486 



243. Bipinnarian larva of Star-fish, after Muller, . . . 487 



244. Pluteus-larva of Echinus, after Miiller, . . . . .489 



245. Cells of Lepralice, after Johnston, ..... 492 



246. Laguncula repens, after Van Beneden, ..... 493 



247. Bird's-head processes of Cellularia and Bugula, after Johnston and Busk, 498 



248. Amaroucium prolifei^um, after Milne-Edwards, . . . 501 



249. Botryllus violaceus, Ditto . . . .502 



250. Perophora, after Lister, ....... 503 



251. Transverse Section of Pinna, ..... 507 



252. Membranous basis of Ditto . . . . . .507 



253. Vertical Section of Ditto . . ... . 507 



254. Oblique Section of Ditto . . . . . .508 



255. Section of hinge-tooth of Mya, ..... 509 



256. Nacre of Avicula, . . . . . 510 



257. Tubular shell-structure of Anomia, ..... 512 



258. Vertical Section of shell of Unio, ..... 512 



259. Internal surface of shell of Teretoatula, .... 513 



260. External Ditto Ditto . . . . .513 



261. Vertical Sections of Ditto ..... 514 



262. Horizontal Section of shell of Terebratula bullata, . . .514 



263. Ditto Ditto of Megerlia lima, . . . 514 



264. Ditto Ditto of Spiriferina rostrata, . . . 514 



265. Palate of Helix hortensis, . . . . . 518 



266. Ditto of Zonites cellarius, . . . . . .518 



267. Ditto of Trochus zizyphinus, . . . . . 519 



268. Ditto of Doris tuberculata, . . . . . .519 



269. Ditto of Buccinum, under polarized light, .... 521 



270. Embryoes of Nudibranchs, after Alder and Hancock, . . . 522 



271. Embryonic development of Purpura, .... 523 



272. Latter stages of the same, .... llM . 525 



273. Structure of Polycelis, after Quatrefages, . . . , .vr> 534 



274. Circulation of Terebella, after Milne-Edwards, . . . . 535 



275. Ammothea pycnogonoides, after Quatrefages, . .*---; f! ,. 540 



276. Cyclops quadricornis, after Baird, . ... . . 543 



277. Development of Balanus, after Bate, .... 549 



278. Metamorphoses of Carcinus, after Couch, . . . .551 



279. Scale of Morpho Menelaus, ...... 557 



280. Battledoor scale of Polyommalus argus, after Quekett. . . . 557 



281. Scales of Podura plumbea, . . . .'. . 558 



282. Hairs of Myriapod and Dermestes, ..... 560 



283. Head and eyes of See, . . . . . . 561 



284. Section of Eye of Melolontha, after Strauss-Durckheim, . . 562 



285. Antenna of Cockchafer, ...... 565 



286. Portions of ditto more highly magnified, . . . 565 



287. Tongue of Fly, ....... 566 



288. Tongue, &c., of Honey Bee, . . . . . .567 



289. Proboscis of Vanessa, ...... 568 



290. Tracheal system of Nepa, after Milne-Edwards, . . .571 



