^{page 399 note 1} Garstang, , Report on Nudibranchiate Mollusca of Plymouth Sound, Journ. Mar. Biol. Assoc., N. S., vol. i, No. 2, 1889, pp. 373—198.Google Scholar

^{page 399 note 2} Herdman, , On the Structure and Function of the Dorsal Papilla in Nudibranchiata, Rep. Brit. Assoc., 1889, Section DGoogle Scholar; and Quart. Journ. Micr. Sci., xxxi. Prof. Herdman kindly sent me copies of these papers, which, though containing views similar to some expressed in my previous Report, were written for the most part before its publication.

^{page 400 note 1} Herdman, and Clubb, , Third Report on Nudibranchiata of L.M.S.C. District, Trans. Liverpool Biol. Soc., iv, 1890, pp. 150—163Google Scholar; and Nature, June 26th, 1890, pp. 201—203.

^{page 402 note 1} See under Oscanius membranaceus, infra, p. 419.

^{page 403 note 1} In recording a specimen found on the shore at St. Andrews, Prof. Mclntosh remarks, “No spots or other markings were present on the dull olive hue of the body” (Mar. Inv. and Fish, St. Andrews, p. 84).

^{page 405 note 1} Hunt, , On some Large Aplysiæ taken in Torbay in 1875, Trans. Devonshire Assoc, vol. ix, 1877, pp. 400—403Google Scholar; On the Growth of Aplysæ in Torbay, Trans. Devonshire Assoc., x, 1878, pp. 611—617.Google Scholar

^{page 406 note 1} In my formulae for the teeth of Aplysia the three, or sometimes four, rudimentary lateral teeth at the extremities of the transverse rows are always included. In comparing these formulæ with those given by Mr. Hunt it should be remembered that Mr. Hunt counts only the perfectly developed lateral teeth.

^{page 408 note 1} The italics are mine.

^{page 408 note 2} The Lingual Membrane of Mollusca, Trans. Mier. Soc, xvi, N. S., pl. x, fig. 42.Google Scholar

^{page 410 note 1} Notizie Biolog. rig. spec, il Periodo di maturitá, ecc., Mitt. Zool. Stat. Neap., viii, 1888, pp. 415, 416.Google Scholar

^{page 410 note 2} Loc. cit., 1878, p. 615.

^{page 410 note 3} Rep. Brit. Assoc., vol. xxxv, Birmingham, 1865.Google Scholar

^{page 418 note 1} Clark, loc. cit., p. 269.

^{page 418 note 2} Cocks, Contributions to the Fauna of Falmouth, Trans. Cornwall Polytech. Soc, 1849.

^{page 418 note 3} Hunt, , Notes on Torbay, Trans. Devon. Assoc., vol. x, 1878, pp. 189, 190.Google Scholar

^{page 419 note 1} See Pelseneer, , Sur l’Epipodium des Mollusques, Bull. Sci. Fr. Belg., 1888, p. 192, &c.Google Scholar

^{page 419 note 2} Herdman, and Clubb, , Third Report on the Nudibranchiata, Trans. Liverpool Biol. Soc., iv, p. 147.Google Scholar

^{page 419 note 3} Bateson, , The Sense Organs and Perceptions of Fishes, this Journal, N. S., vol. i, p. 247.Google Scholar

^{page 420 note 1} Verrill, , Rep. Invert. Anim. Vineyard Sound, U.S. Fish. Rep., 1873, pp.Google Scholar

^{page 421 note 1} Giard, Bull. Sci. France et Belg., 1888, p. 502.

^{page 422 note 1} Some Additions to the Fauna of the Firth of Forth, with Notes of some Rare East Coast Forms, Seventh Ann. Rep. Fish. Board for Scotland, 1889, pt. 3, pp. 324, 325.

^{page 423 note 1} See Verrill, , Rep. Invert. Vineyard Sound, 1873, pl. xxv, fig. 175.Google Scholar

^{page 424 note 1} I need hardly Bay that I owe the identification of many of these algæ to my friend Prof. Johnson, who has rendered me much help in this way during his visits to Plymouth.

^{page 426 note 1} Bergh, , Die cladohepatischen Nudibranchien, Zool. Jahrbüch., Abth. f. Systematik, Bd. v, 1890, p. 50.Google Scholar

^{page 427 note 1} I have indeed since found two other specimens in the preserved collection of Antennularia ramosa.

^{page 427 note 2} Loc. cit., p. 50: “Die Lomanoten scheinen ziemlich träge Thiere zu sein, iiber deren biologische Verhaltnisse nichts bekannt ist.”.

^{page 429 note 1} The pleuropodial fins of Lobiger are, according to M. Vayssière, folded over the back of the animal when at rest, as in Aplysia, Baminea, &c. It is of interest to notice that this habit is still persistent in Lomanotus (see Thompson, l. c, p. 50; and previous Report, 1. c, p. 187).

^{page 429 note 2} Cf. Alder and Hancock on Scyllæa (Monograph): “The orifice [of the rhinophoral sheath] inclines forwards, and there is a thin, arched, crest-like appendage behind it.”

^{page 429 note 3} Cf. Bergh (l. c , p. 5), Bei den Dendronotiden, Sornelliden, und Scyllæiden verschmelzen die vordersten Papillen mit dem Stiele der Rhinophorien.

^{page 430 note 1} L. c, pp. 4, 49, &c.

^{page 430 note 2} Manuel de Conchyliologie, pp. 526, 535, &c.

^{page 431 note 1} Herdman, , On the Structure and Function of the Dorsal Papillæ in Nudibranchiata, Report Brit. Assoc, 1889, Sect. D, and Quart. Journ. Micr. Sci., xxxi, p. 56.Google Scholar

^{page 432 note 1} Cf. McIntosh, Mar. Inv. and Fishes, St. Andrews, 1875, p. 86. Mr. Vallentin finds the species common at Falmouth on Obelia geniculata. I have found it on this Hydroid occasionally at Plymouth.

^{page 432 note 2} L. c, pp. 175, 191. Sagartia parasitica on the former page was obviously an error, and I take this opportunity of correcting it.

^{page 434 note 1} The same was the case with a number of the posterior cerata in one of the individuals taken on October 24th.

^{page 436 note 1} Loc. cit., p. 5.

^{page 439 note 1} Third Report on Nudibranvhiata, l. c., pp. 140—143.

^{page 443 note 1} Giard, Bull. Sci. France et Belg., 1888, p. 502.

^{page 443 note 2} For the classification of the Anthobranchiata, cf. Abraham, Proc. Zool. Soc, 1877, pp. 196—269, pls. xxvii—xxx.

^{page 443 note 3} Bergh, , Gattungen nordischer Doriden, Arch. f. Naturgesch., Jarg. 45, Bd. i, pp. 340—369.Google Scholar

^{page 444 note 1} Mr. Poulton (The Colours of Animals, 1890, p. 108) has mentioned the probable existence in this species of the power of adjustment of its colour to that of its surroundings. Prof. Stewart’s specimens, however, were in all probability not tuberculata, but a distinct species.

^{page 446 note 1} Bergh, , Gattvngen nord. Doriden, Arch. f. Naturgesch., lv, p. 348.Google Scholar

^{page 449 note 1} This average is probably a little too high for the individuals which are still some distance from the shore. On October 16th, of seven specimens dredged near the Duke Rock, one was inch, one inch, four inch, and one inch in length.

^{page 451 note 1} Huxley, Morphology of the Cephalous Mollusca, Phil. Trans., 1852.

^{page 451 note 2} Cf. Lankester, Mollusca, Encycl. Brit., 9th ed., vol. xvi; Fischer, Manuel de Conchyliologie, 1887, p. 518 (Fischer’s view is that the nothæum of Doris represents at the same time both the “epipodial” lobes of Elysia or Aplysia fused in the median line and the cephalic disc of Philine); Herdman and Clubb, Third Report on the Nudibranchiata, l. c, p. 147 ; also my Report on the Nudibranchiata, l. c., p. 181.

^{page 452 note 1} Bergh, , Die Qattung Goniodoris, Malakozoologische Blätter, Neue Folge, Bd. i, 1880, pp. 123, 124, and pi. iv.Google Scholar

^{page 452 note 2} Herdman, and Clubb, , Second Report on the Nudibranchiata, Proc. Liverp. Biol. Soc., iii, p. 227.Google Scholar

^{page 453 note 1} Giard, Arch. Zool. Exp., ii, 1873, p. 487.Google Scholar

^{page 453 note 2} See Bergh, , Die Gattung Goniodoris, Malak. Blätt., i, p. 127.Google Scholar

^{page 453 note 3} Herdman, , First Report on the Nudibranchiata, Liv. Mar. Biol. Comm. Rep., i, 1886, p. 270Google Scholar; and Notes on the Marine Inv, Fauna, Isle of Man, do., do., p. 319.

^{page 454 note 1} Bergh, , Ueber die Gattung Idalia, Arch für Naturgesch., xlvii, i, p. 7Google Scholar. See also Norman on the name Idalia, loc. cit., p. 74.

^{page 454 note 2} Herdinan and Clubb, Third Report, p. 134; cf. also the Second Report, p. 227, and First Report, 1886, p. 270, and Thompson, Ann. Mag. Nat. Hist., 1860, p. 51.

^{page 455 note 1} See ProfJohnson’s, paper on The Flora of Plymouth Sound, this Journal, New Series, I, iii, pp. 297, 298.Google Scholar

^{page 455 note 2} I have followed Dr. Norman in placing ocellata as a variety of Lessonii. Herdman and Clubb (Second Report, 1889, p. 227) have noticed the intermediate variations, but it is interesting to note that the type and the variety seem to live, as a rule, under different conditions of depth and food (see Alder and Hancock, Monograph).