OCR Text |
Show 1900.] FROM THE FALKLAND ISLANDS. 565 the eyes are simple. Professor Smith, in describing his Scyphacella arenicola, says " eyes prominent, round," and " eyes black," a twofold notice from which so important a character as " eyes simple " could scarcely have been omitted had it been applicable. The figure of the species by Harger (Bep. U.S. Comm. Fisheries for 1878, pt. 6, pi. 1. fig. 2) shows well-developed eyes with numerous components. Gen. TRICHONISCUS J. F. Brandt. 1833. Trichoniscus, Brandt, Conspectus Crust. Oniscodorum, p. 12 (Bull. Soc. Moscou, vol. vi. p. 174). 1838. Itea, C. L. Koch, Deutschlands Crustaceen, 22 (162), no. 16. 1840. Trichoniscus, Milne-Edwards, Hist. Nat. Crust, vol. iii. p. 174. 1844. Itea, Zaddach, Synopseos Crust. Prussicorum Prodromus, p. 15. 1853. Styloniscus (part.), Dana, U.S. Expl. Exp. vol. xiii., Crust. p. 736. 1857. Philougria, Kinahan, Nat. Hist. Bev. vol. iv. p. 281. 1868. Philougria, Bate & Westwood, Brit. Sess.-eyed Crust. vol. ii. p. 454. 1870. Trichoniscus, Budde-Lund, Naturh. Tidsskr. ser. 3, vol. vii. p. 227. 1885. Trichoniscus, Budde-Lund, Crust. Isop. Terrestria, p. 243. 1886. Philygria (preocc. Diptera, 1844), Thomson & Chilton, Tr. New Zealand Inst. vol. xviii. p. 157. 1886. Philygria, Chilton, ibidem, p. 159. 1898. Trichoniscus, Sars, Crustacea of Norway, vol. ii. p. 160. To this genus Budde-Lund in 1885 assigns nine species, one of them being T. asper Koch, found in amber, and another the Scyphacella arenicola of Smith, already referred to. He makes the Trichoniscus leydigi of Weber a synonym of his own T. albidus, but this decision is not admitted by Sars. Dollfus added to the genus the species chavesi in 1888, insularis in 1889, and with some doubt murrayi and australis in 1890. In 1898 Sars instituted a new genus, Trichoniscoides, to receive Trichoniscus albidus Budde- Lund, T. leydigi Weber, and perhaps T. cavernicola Budde-Lund. He does not mention Trichoniscus vividus Koch, but that species should probably be transferred, as it has simple eyes ; and the most prominent, though not of necessity the most important, distinction of the new genus is that the eyes are simple or wholly wanting, whereas in Trichoniscus they are " small, but distinct, consisting of only 3 visual elements imbedded in a dark pigment." In 1885 Chilton described a marine species from New South Wales as Philougria marina, but the eyes apparently have numerous visual elements, the mandibles show no molar, and the other mouth-organs are undescribed ; so that this species cannot be included in Trichoniscus. In 1886 the same author described Philygria thom-soni from New Zealand, and this appears to be a true Trichoniscus. |