^{page 270 note *} Quart. Journ. Micros. Science, Aug. 1897.

^{page 271 note *} Quart. Journ. Micros. Science, 1886.

^{page 272 note *} A. Sedgwick, loc. cit., p. 67.

^{page 272 note †} Cf. development of Serpula, Peripatus, and Mollusca.

^{page 273 note *} Brooks, W. K., The Genus Salpa, BaltimoreGoogle Scholar.

^{page 273 note †} A. T. M., , Natural Science, March 1897Google Scholar.

^{page 274 note *} Macbride, E. W., Natural Science, January 1897Google Scholar.

^{page 274 note †} Cf. the suggestive remarks of Korschelt and Heider (pp. 344–345, English translation).

^{page 274 note ‡} By this it is not implied that this organism was morphologically comparable to the medusae of the present day. To this view (Kleinenberg, Balfour) it has been objected by Korschelt and Heider (pp. 342–343, English translation) that the medusa presents a higher type of locomotion, and we may add of ingestion. Another indicated difficulty is the absence, in medusæ, of an apical nervous system. It has been assumed below that the apical ganglion was present in the pelagic cœlomate ancestor, and that in such a form as the trochosphore it has become secondarily shifted to the new apical pole at the apex of the pre-oral lobe. For figure of this Stage I., see Quart. Journ. Micros. Science, vol. xxxviii. p. 325Google Scholar.

^{page 276 note *} For figures of Stage II., see Quart. Journ. Micros. Science, vol. xxxviii. p. 327Google Scholar, and of this Stage III. on p. 328.

^{page 276 note †} See Zool. Anzeiger, Nos. 501, 502, and 503.

^{page 277 note *} Zool. Anzeig., 501–503.

^{page 278 note *} It will be seen that in nearly all these features Actinotrocha is the embodiment of this morphological conception of the ancestor from which all the Archi-cœlomata have been derived, and it is remarkable how this larva might be, and indeed has been, mistaken for that of nearly all the groups of Archi-cœlomata in turn. Cf. Q. J. M. S., vol. xxxviii. p. 282.

^{page 281 note *} Butschli, O.Zeitschrift Wiss. Zool., xxiii., 1873Google Scholar.

^{page 281 note †} “If it is permissible to refer the efferent sexual ducts to metamorphosed nephridia, we should have to ascribe to Sagittœ at least two trunk somites, and accordingly explain the Chœtognatha as forms in which, perhaps in connection with the manner of locomotion, a primitive segmentation of the body has been retained in a degenerated form only.”—Text-Book of Embryology, by Korschelt, and Heider, (Translation), p. 371Google Scholar.

^{page 281 note ‡} An. Mus. Nat. Hist., Marseille, ii., 1884–1885Google Scholar.

^{page 282 note *} Q. J. M. S., August 1897, “On the Diploohorda.”

^{page 283 note *} Harmer, S. F., Challenger Reports, vol. xxGoogle Scholar., and A. T. M., , Q. J. M. S., August 1897Google Scholar.

^{page 284 note *} Joubin, , Arch. Zool., Exper. (2) ivGoogle Scholar.

^{page 285 note *} Lehrbuch, d. v. Entwickel, d. Wirb. th., p. 1251.

^{page 286 note *} Mittheil, Neap. Zool. Stat., IV.

^{page 286 note †} Jenaische Zeitsch., 1883.

^{page 286 note ‡} Zoolog. Anzeiger, viii., 1885Google Scholar.

^{page 286 note §} Phil. Trans., 148, 1858Google Scholar.

^{page 286 note ∥} Proc. Boston Soc. N.H., xv. p. 315–372Google Scholar.

^{page 287 note *} Cf. Korschelt and Heider, loc. cit., p. 1238, fig. 720.

^{page 288 note *} Loc. cit., pi. xl. figs. 33 and 35.

^{page 288 note †} Loc. cit., pi. xiv. fig. 20.

^{page 288 note ‡} Cf. Caldwell, , Proc. Roy. Soc., 1883Google Scholar, and Lankester, E. R., Ency. Brit., ‘Polyzoa,’ p. 171Google Scholar.

^{page 289 note *} Jenaiscke Zeitschrift, 1883. Cf. Hertwig.

^{page 289 note †} Loc. cit.

^{page 290 note *} Macbride, E. W., Quart. Journ. Micro. Sci., vol. xxxiv. p. 149Google Scholar.

^{page 290 note †} Bury, H., Quart. Journ. Micro. Sci., vol. xxxviii. p. 129Google Scholar, and Field, G. W., Q. J. M. S., vol. xxxivGoogle Scholar.

^{page 290 note ‡} Q. J. M. S., App. 1889, and Phil. Trans. Roy. Soc. Lond., vol. clxxix.

^{page 290 note §} Q. J. M. S., vol. xxxviii.

^{page 290 note ∥} Proc. Roy. Soc., vol. liv.

^{page 291 note *} “On the Diplochorda,” Q. J. M. S., August 1897.

^{page 292 note *} Cori. Zeits. f. w. Zool., Bd. 51.

^{page 294 note *} Huxley, T. H., Journ. Linn. Soc., vol. xiiGoogle Scholar.

^{page 294 note †} Caldwell, W. H., Quart. Journ. Micro. Soc., 1885Google Scholar.

^{page 295 note *} Patten, W., Arb. Zool. Inst. Wien, 1886Google Scholar.

^{page 296 note *} Bury, H., Phil. Trans. Roy. Soc. Lond., vol. clxxixGoogle Scholar.

^{page 297 note *} In certain pelagic larvæ, e. g. Bipinnaria, the functional œsophagus is early formed although not actually part of the blastopore. In these the two lateral cœlomes move forwards later to form the protocœle.

^{page 297 note †} Salenka, , Jena. Zeits., xxii., 1888Google Scholar.

^{page 298 note *} Proc. Royal Soc. Edin., 1895–1896, p. 63Google Scholar.

^{page 299 note *} Quart. Journ. Micro. Science, August 1897.

^{page 299 †} Macbride, E. W., Quart. Journ. Micros. Science, Jan. 1898Google Scholar.

^{page 300 note *} Cf. Willey, A., Amphioxus and the Ancestry of the Vertebrates, pp. 128–129, and 279Google Scholar.

^{page 303 note *} Agassiz, A., Annals Lyc. Nat. Hist., New York, vol. viiiGoogle Scholar.

^{page 304 note *} Kleinenberg, N., Zeitsch. wiss Zool., vol. xliv., 1886Google Scholar.

^{page 306 note *} Cf. Shipley, A. E., Quart. Journ. Micros. Sci., xxxiGoogle Scholar. There are difficulties in the way of this author's comparison of Phoronis and Phymosoma. If we accept his comparison in figs. 31 and 32, then the pre-oral lobe must be looked for, not as indicated by Mr Shipley, on the anal side of the tentacles, but on the oral side, where the epistome is found in Phoronis.

^{page 306 note †} Traité de Zoologie Concrête, vol. v.