[185] Möbius, Report on ‘Pommerania’ Exped. pp. 138–141.

[186] Journ. de Conchyl. xxiii. 1875, p. 105.

[187] J. W. Taylor ut sup. p. 300.

[188] Sci. Trans. R. Dubl. Soc. (2) iv. p. 555.

[189] J. S. Gibbons, Journ. of Conch. ii. p. 129.

[190] C. H. Morris, ibid. vii. p. 191.

[191] F. M. Hele, ibid. iv. p. 93.

[192] T. D. A. Cockerell, Science Gossip, 1887, p. 67.

[193] J. G. Jeffreys, British Conchology, vol. i. p. 214.

[194] Journ. of Conch. vi. p. 123.

[195] Phil. Trans. 1889, vol. 180 B, p. 207. A somewhat similar case (the celebrated Steinheim series of Planorbis) is dealt with by Hilgendorf, MB. Akad. Berl. 1866, p. 474; and Hyatt, Proc. Amer. Ass. Sc. xxix. p. 527.

[196] J. B. Bridgman, Quart. Journ. Conch. i. p. 70.

[197] W. C. Hey, Journ. of Conch. iii. p. 268.

[198] Zool. Anz. xiii. p. 662.

[199] J. Madison, Journ. of Conch. v. p. 260.

[200] Quart. Journ. Conch. i. 339.

[201] Whitfield, Bull. Amer. Mus. N. H. i. p. 29.

[202] Amer. Nat. xiv. p. 51.

[203] Animal Life, Ed. 1, p. 160 f.

[204] Conch. Syst. ii. p. 262 n.

[205] P. L. Simmonds, Commercial Products of the Sea, p. 278.

[206] Benderloch, p. 118.

[207] C. Hedley in J. P. Thomson, Brit. New Guinea, p. 283.

[208] Most of the above facts are derived from a study of a collection of native implements, weapons, ornaments, etc., in the Antiquarian Museum at Cambridge.

[209] Thurston, Notes on the Pearl and Chank Fisheries, Madras, 1890.

[210] See in particular, P. L. Simmonds, The Commercial Products of the Sea.

[211] H. Friend, Field Club, iv. 1893, p. 100.

[212] Nature, xxxi. 1885, p. 492.

[213] W. Anderson Smith, Benderloch, p. 173.

[214] Dominique, Feuill. Nat. xviii. p. 22.

[215] SB. Nat. Fr. Berl. 1889, p. 197.

[216] A. Adams, Voyage of the ‘Samarang,’ ii. p. 308.

[217] Much information has been derived, on this subject, from Bertram’s Harvest of the Sea, Simmonds’ Commercial Products of the Sea, the publications of the Fisheries Exhibition, especially vol. xi. (Anson and Willett); see also Philpots, Oysters and all about them.

[218] Juvenal, Sat. iv. 140–142.

[219] Hist. Nat. ix. 79.

[220] Vol. Max. ix. 1.

[221] Quart. Journ. Micr. Sc. xxvi. p. 71.

[222] See G. H. Lewes, Sea-side Studies, p. 339.

[223] Bull. U.S. Fish. Comm. v. p. 161.

[224] W. Anderson Smith, Loch Creran, p. 228.

[225] Longmans’ Magazine, June 1889.

[226] St. James’s Gazette, 6th January 1893.

[227] Also at Arcachon (W. A. Herdman, Nature, 1893, p. 269).

[228] See especially Hoek, Tijdschr. Ned. Dierk. Vereen, Suppl. Deel, i. 1883.

[229] Benderloch, p. 136.

[230] This is the view of E. Ray Lankester, Quart. Journ. Micr. Sc. xxvi. 80.

[231] De Quatrefages, Rambles of a Naturalist.

[232] Quoted by Jeffreys, Brit. Conch., ii. p. 109.

[233] M. S. Lovell, Edible Mollusks, p. 49.

[234] Science, vii. p. 175.

[235] Hist. Nat. ix. 82.

[236] De re rustica, iii. 14.

[237] Epistles, i. 15.

[238] Hor. Sat. II., iv. 58, tr. Conington.

[239] Roberts, Zoologist, 1885, p. 425.

[240] Hist. Nat. xxx. 15, 19.

[241] Science Gossip, 1891, p. 166.

[242] Jeffreys, Brit. Conch. iii. p. 355.

[243] W. Clark, Mag. Nat. Hist. xvi. p. 466.

[244] Examples will be found in Journ. Linn. Soc. Zool. xi. p. 90; Ann. Sc. Nat. xx. p. 472; Zeit. wiss. Zool. xxiv. p. 419.

[245] Herdman, Proc. Liverp. Biol. Soc. iii. p. 30.

[246] Garrett, Journ. Ac. Nat. Sc. Phil. viii. (1880).

[247] J. Bladon, Zoologist, xvi. p. 6272.

[248] Lo Bianco, MT. Zool. Stat. Neap. viii. p. 414.

[249] Animal Life, pp. 126, 135.

[250] R. Rimmer, Land and Fresh-Water Shells, p. 119.

[251] Journ. de Conch. ii. p. 245.

[252] Journ. de Conchyl. iii. p. 107.

[253] Jeffreys, Brit. Conch. iii. p. 359; Sauvage, Journ. de Conchyl. xxi. p. 122.

[254] Hermaphroditism seems to occur in (a) whole families, e.g. Anatinidae and the Septibranchia; (b) genera, e.g. Cyclas, Pisidium; (c) single species, e.g. in the generally dioecious genera Ostrea, Pecten, Cardium.

[255] δὐω, two; μόνος, single; γόνος, semen; πόρος, passage.

[256] Von Brunn, Arch. Mikr. Anat. xxiii. p. 413.

[257] Hist. Anim. v. 6 and 12, iv. 1, ed. Bekker, 1837.

[258] ‘On pourra constater si ce ne seraient pas des parties détachées de quelque céphalopode dans le but de servir à le fécondation,’ Hist. Nat. Helminthes, 1845, p. 482.

[259] Steenstrup, Ann. Mag. Nat. Hist. (2), xx. p. 81 f.

[260] C. Ashford, Journ. of Conch. iii. p. 239, iv. pp. 69, 108.

[261] W. E. Collinge, Zoologist, 1890, p. 276.

[262] Pelseneer, Comptes Rendus, cx. p. 1081.

[263] Kon. Vet. Akad. Handl. 1848, pp. 329–435.

[264] P. Z. S. 1891, p. 52 f.

[265] The result of some experiments by Professor Herdman upon Littorina rudis, tends to show that it can live much better in air than in water, and goes far to support the view that the species may be undergoing, as we know many species must have undergone (see p. 20), a transition from a marine to a terrestrial life. It was found that marked specimens upon the rocks did not move their position for thirty-one successive days (Proc. Liverp. Biol. Soc. iv. 1890, p. 50).

[266] Diminutive of κτείς, a comb.

[267] Stoliezka, quoted in Journ. de Conch. xviii. p. 452.

[268] ζύγος, a yoke, from the symmetrical position of the branchiae.

[269] Pelseneer, ‘Challenger’ Reports, vol. xxiii. part lxvi.

[270] Zoologist, xii. p. 4248.

[271] Mollusques de France, i. p. 81.

[272] N. Denk. Schw. Ges. xxix. (2) p. 196 f.

[273] Bergh, Morph. Jahrb. x. p. 172.

[274] P. Fischer, Journ. de Conch. ix. p. 101.

[275] Bull. Mus. C. Z. Harv. xviii. p. 434.

[276] Pelseneer, Comptes Rendus, cvi. p. 1029.

[277] E.g. Kollmann, Zeit. wiss. Zool. xxvi. p. 87.

[278] Proc. Roy. Soc. 1873, p. 70.

[279] Griesbach (Arch. mikr. Anat. xxxvii. p. 22) finds haemoglobin in several bivalves, e.g. Poromya granulata, Tellinata planata, Arca Noae, and Pectunculus glycimeris.

[280] Trans. Roy. Soc. N. S. Wales, xxii. p. 106.

[281] Pelseneer, Comptes Rendus, cx. p. 154.

[282] Science, iv. p. 50.

[283] P. Fischer, Journ. de Conchyl. (3) xxvii. p. 201.

[284] Journ. of Conch. vi. p. 349 ff.

[285] Quart. Journ. Micr. Sc. N.S. xv. p. 37.

[286] Ann. Mag. Nat. Hist. (2), xx. p. 336.

[287] V. Willem (Arch. Biol. ut infr.) denies this, and declares that Cyclostoma is only very sensitive to movements. The present writer has often approached, with the greatest care, a crawling Cyclostoma, but it always withdrew into its shell or fell to the ground when approached within about 10 or 12 inches.

[288] Arch. Biol. xii. 1892, p. 57.

[289] ‘Challenger’ Reports, Zoology, vol. xxvii. part lxxiv. p. 3.

[290] Animal Life, p. 372 f.

[291] Bergh, Morph. Jahrb. x. p. 172.

[292] Ann. Mag. Nat. Hist. (5) xiv. p. 141.

[293] The nature of the grouping of the eyes into rows varies considerably in different species. As a rule, the rows radiate from the beak, but occasionally they run parallel to the girdle. In Tonicia lineolata Fremb., they are grouped, as it were, under the shelter of strongly marked longitudinal wavy lines.

[294] Shell-Eyes in other Mollusca.—The Rev. J. E. Tenison-Woods (Trans. Linn. Soc. N. S. Wales, xxii. p. 106) is of opinion that ‘shell-eyes’ are by no means confined to the Chitonidae, but that, in fact, multiplicity of eyes of this kind is the rule rather than the exception among the Mollusca. He finds (1) exceedingly minute and numerous ‘eyes’ on the outer surface of the shell in both univalves and bivalves; (2) large and solitary ‘eyes’ in the shell substance; (3) eyes on the mantle lobes in both univalves and bivalves; (4) eyes on the opercula.

[295] Mitth. Stat. Zool. Neap. v. p. 447 ff.

[296] W. Patten, Mitth. Zool. Stat. Neap. vi. (1886) pp. 546, 605 f.

[297] Benderloch, p. 136.

[298] Quart. Journ. Micr. Soc. xx. p. 443.

[299] Quart. Journ. of Conch. i. p. 368.

[300] British Conchology, i. p. xxviii.

[301] Science Gossip, 1865, p. 259.

[302] Mollusques de France, i. p. 130.

[303] E.g. Sochaczewer, Zeits. wiss. Zool. xxxv. p. 30.

[304] Zool. Anz. 1882, p. 472.

[305] Zoologist, iv. p. 1266.

[306] Journ. Mar. Biol. Ass. N.S. i. p. 217.

[307] Moquin-Tandon, Moll. de France, i. p. 133.

[308] Zool. Jahrb. Anat. iv. (1890) p. 501.

[309] Baudon, Rév. Mag. Zool. 1852, p. 575.

[310] Arch. Zool. Exp. Gén. (2) v. 1887, p. 2; compare also C. H. Hurst, Natural Science, ii. pp. 360, 421.

[311] Compare Pelseneer, Bull. Sci. Fr. Belg. (3) xix. pp. 107, 182.

[312] Pelseneer, Arch. Biol. viii. p. 723.

[313] Also known as labial and supra-oesophageal ganglia.

[314] Wivén, however (K. Sv. Vet. Ak. Handl. xxiv. 1892, No. 12), describes transverse connectives in Chaetoderma.

[315] στρεπτός, twisted; εὐθύς, straight.

[316] With the exception of Actaeon, which is streptoneurous (Bouvier, Comptes Rendus, cxvi. p. 68).

[317] This fusion of the cerebral and pleural ganglia and the consequent union of the cerebro-pedal and pleuro-pedal commissures can be recognised by sections of the mass (Pelseneer, Comptes Rendus, cxi. p. 245).

[318] There is practically no pharynx in the Pelecypoda, the mouth opening directly into the oesophagus.

[319] Radere, to scrape; ὸδούς, tooth; φέρειν, to carry.

[320] The mechanism of the radula has been dealt with by Geddes, Trans. Zool. Soc. x. p. 485. Rücker has observed (Ber. Oberhess. Gesell. Nat. Heilk. xxii. p. 207) that the radula in Helix pomatia is the product of five rows of cells; the use of the first row is uncertain, the second forms the membrane of the radula, while rows three to five originate the teeth.

[321] Jahrb. Deut. Malak. Gesell. iii. p. 193.

[322] The whole of the radulae and jaws figured in this work are taken from the original specimens in the collection of the Rev. Prof. H. M. Gwatkin, who has always been ready to give me the run of his cabinets, which probably contain the finest series of radulae in the world. To his kindness I owe the following description of the process of mounting: “The first step is to obtain the radula. Dissection is easy in species of a reasonable size. On opening the head from above, so as to lay open the floor of the mouth, the radula itself is seen in most of the marine species, though in others it is contained in a sort of proboscis; and in the Pulmonata and others the student will find the buccal mass, with commonly a brown mandible at its front end, and the lingual ribbon in its hinder part. The teeth may be recognised by their silvery whiteness, except in a few cases like Patella and Chiton, where they are of a deep brown colour. When obtained, the radula may be cleaned by boiling in a solution of caustic potash. There is no risk of injury if the solution is not too strong.

“Smaller species may be treated more summarily. The proboscis, the buccal mass, or even the whole animal may be thrown into the potash solution and boiled till scarcely anything is left but the cleaned radula. Remains of animals dried inside the shell may be similarly dealt with, after soaking in clean water. With a little care, this process will answer for shells down to the size of Ancylus or Rissoa. The very smallest (Carychium, Tornatellina, Skenea, etc.) must be crushed on the slide and boiled on it, after removing as much as possible of the broken shell. The radula can then be searched for under the microscope, and washed and mounted on the slide.

“The student must be warned that though the general process is simple, there are difficulties in particular cases. In the Pulmonata, for example, membranes on both sides of the radula need careful removal. Murex, Purpura, and most of the Taenioglossa have the side teeth folded down over the central, so that the arrangement is not well seen till they have been brushed back. The Cones, again, have no basal membrane at all, so that if the potash is not used with great care, the single teeth will fall asunder and be lost. Perhaps the worst case is where a large animal has a radula as small as that of a Rissoa, like Turritella, Harpa, or Struthiolaria, or where the radula is almost filmy in its transparency, like those of Actaeon and the small Scalaria.

“When once the radula is laid out, the mounting is commonly easy. Canada balsam makes it too transparent. Fluids may be used, and are almost necessary for thick radulae like those of large Chitons; but the best general medium is glycerine jelly. It runs under the cover glass by capillary attraction, and may be boiled (though only for a moment) to get rid of air bubbles. It should then be left unfinished for several weeks. If cracks appear, the reason is either that the jelly is a bad sample, or that it has been boiled too long, or (commonly) that the object is too thick; and there is not often any difficulty in remounting. I have no serious complaint of want of permanence against the medium, if I may speak from a pretty wide experience during the last twenty years.”

[323] The substance both of the jaw and radula is neither crystalline nor cellular, but laminated. Chitin is the substance which forms the ligament in bivalves, the ‘pen’ in certain Cephalopoda, and the operculum in many univalves. Neither silica nor keratine enter into the composition of the radula.

[324] τόξον, arrow; ῥάχις, ridge, sharp edge; ταινία, ribbon; πτηνός, winged; γυμνὀς, bare; ῥιπίς, fan; δοκός, beam.

[325] V. concinna, according to Schacko (Conch. Mitth. i. p. 126, Pl. xxiv. f. 5); the lateral is large, strong, unicuspid on a broad base.

[326] In some cases (e.g. Hyalinia inornata) the laterals are very few, while in Zonites laevigatus the first side tooth is more of a marginal than a lateral.

[327] Semon, Biol. Centralbl. ix. p. 80.

[328] According to Moquin-Tandon (Moll. de France, i. p. 44) this process in Bithynia is attached by one end to the wall of the stomach. Vivipara, with two jaw pieces, does not possess this stylet; Bithynia, which does possess it, has no jaw.

[329] J. H. Vanstone, Journ. Linn. Soc. xxiv. p. 369.

[330] Biol. Centralbl. vii. p. 683; SB. Ges. Nat. Fr. 1890, p. 42; Mag. Nat. Hist. (2) v. 1850, p. 14.

[331] νεφρός, kidney.

[332] Ann. Mag. Nat. Hist. (2) xvi. p. 298.

[333] See, for instance, Quart. Journ. Conch. i. p. 340 (Cyl. Raveni): Jahrb. Deut. Malak. Gesell. 1879, p. 98 (Clausilia dubia).

[334] Cailliaud, Journ. de Conchyl. vii. p. 231; Gassies, ibid. p. 44.

[335] Arch. Naturgesch. xlii. p. 209.

[336] Dr. W. B. Carpenter, Rep. Brit. Ass. xiii. p. 71; xiv. p. 1; xvii. p. 93; J. S. Bowerbank, Trans. Micr. Soc. i. p. 123; Ehrenbaum, Zeit. wiss. Zool. xli. p. 1.

[337] See also p. 258.

[338] J. E. Gray, Phil. Trans. 1833, p. 774 f.

[339] J. E. Gray, Phil. Trans. 1833, p. 774 f.

[340] Journ. de Conchyl. iv. p. 424.

[341] Journ. de Conchyl. xii. p. 3.

[342] T. Scott, Journ. of Conch., 1887, p. 230.

[343] M. de Villepoix, Comptes Rendus, cxiii. p. 317.

[344] Proc. Ac. Nat. Sc. Phil., 1892, p. 350.

[345] Mr. B. B. Woodward has recently pointed out (P. Z. S. 1892, p. 528) a very remarkable method of shell absorption and growth in Velates and certain other Neritidae.