[420]. Fabricius says of his Pycnogonum (Nymphon) grossipes, “Vescitur insectis et vermibus marinis minutis; quod autem testas mytilorum exhauriat mihi ignotum est, dum nunquam intra testam mytili illud inveni, licet sit verisimile satis,” Fauna Groenlandica, p. 231.
[421]. Loeb (Arch. Entw. Mech. v. 2, 1897, p. 250) also says that the Pycnogons are positively heliotropic.
[422]. See also P. Gaubert, “Autotomie chez les Pycnogonides,” Bull. Soc. Zool. Fr. xvii., 1892, p. 224.
[423]. Cf. Carpenter, Proc. R. Irish Acad. xxiv., 1903, p. 320; Lankester, Quart. J. Micr. Sci. xlviii., 1904, p. 223; Bouvier, Exp. Antarct. Fr., “Pycnogonides,” 1907, p. 7, etc.
[424]. “Nous ne les plaçons ici qu’avec doute,” Règne Anim. éd. 3, tom. vi. p. 298.
[425]. Cf. also J. E. W. Ihle, “Phylogenie und systematische Stellung der Pantopoden,” Biol. Centralbl., Bd. xviii., 1898, pp. 603–609; Meisenheimer, Verh. zool.-bot. Ges. Wien, xii., 1902, pp. 57–64; also Stebbing, in Knowledge, 1902.
[426]. The chelate form of the foremost appendages is of little moment. A chela consists merely of a more or less mobile terminal joint flexing on a more or less protuberant penultimate one, and in the Scorpions, in Limulus, throughout the Crustacea, and even in Insects (cf. vol. vi. p. 554), we see such a structure arising independently on very diverse appendages.
[427]. Cf. Oudemans, Tijdschr. d. Ned. Dierk. Ver. (2), i., 1886, p. 41: “Jedermann weiss nun, dass diese Tiere eine ganz besondere Urgruppe bilden, ohne alle Verwandschaft mit irgend einer anderen Arthropodengruppe.”
[428]. Cole (Ann. Mag. Nat. Hist. (7), xv., 1905, pp. 405–415) has attempted such a phylogenetic classification, starting with Decolopoda, and leading in two divergent lines, through Nymphon and Pallene to the Pycnogonidae, and through Eurycide and Ammothea to Colossendeis. This hint is in part adopted in the subjoined classification. Bouvier, in his recent Report on the Pycnogons of the French Antarctic Expedition (t. cit.), gives reasons for separating the Decolopodidae and Colossendeidae from all the rest. Loman, in Die Pantopoden der Siboga Expedition, 1908, has recently suggested another, and in many respects novel, classification of the whole group.
[429]. See (inter alia) Dohrn, l.c.; E. B. Wilson, Rep. U.S. Fish. Comm. (1878), 1880; Hoek, Chall. Report, 1881; G. O. Sars, Norw. N. Atl. Exp. 1891; Meinert, Ingolf Exped. 1899; Möbius, Fauna Arctica, 1901, Valdivia Exped. 1902; Cole, Harriman Alaska Exped. 1904; Hodgson, Discovery Exped. 1907; Bouvier, Exp. Antarct. Fr. 1907.