REPORT OX THE HETEROPODA. 
11 
1832. Pterotrachea, Wiegmann and Ruthe, Handb. d. Zool., p. 51S. 
1834. Firola, Gray, Griffith’s Anim. King., vol. xii. p. 51. 
1835. Pterotrachea, Oken, Xaturgesch., vol. v. p. 513. 
1836. Firola , d’Orbigny, Toy. Amer. merid., vol. v. pp. 145, 150. 
1836. Anops, id ., op. cit., p. 140. 
1838. Firola, Potiez and Michaud, Galer. Moll., vol. i. p. 47. 
1838. „ Eydoux and Souleyet, L’lnstitut, vol. vi. p. 376 (Auditory Organ). 
1841. „ Cantraine, Mai. Medit., p. 42. 
1841. Pterotrachea, Chiaje, Descriz. e notom. anim. invert. Sicil., voL ii. p. 93. 
1842. „ Gray, Synopsis Brit. Mus., pp. 65, 90. 
1842. Firola, d’Orbigny, Paleont. fran5., Terr, cret., voL ii. p. 18. 
1842. Anops, d’Orbigny, loc. cit., p. 18. 
1843. Firola, Forbes, Rep. Brit. Assoc., p. 132. 
1843. Pterotrachea, Chiaje, Rendicont. Accad. Sci. Soc. Borbon. Hapoli, vol. ii. p. 106. 
1850. Firole, Huxley, Ann. d. Sci. Hat., vol. xiv. p. 193. 
1850. Pterotrachea, Gray, Fig. Moll Anim., vol. iv. p. 100. 
1850. Anops, ibid., loc. cit., p. 100. 
1852. Firola, Souleyet, Voy. “ Bonite,” Zool., vol. ii. p. 345. 
1853. ,, Leuckart, Wiegmann’s Arcbiv f. Haturgesch., p. 253. 
1853. Pterotrachea, Philippi, Handbuch Conch., p. 284. 
1853. Anops, id., op. cit., p. 284. 
1854. Firola, Woodward, Man. Moll., p. 199. 
1854. „ Leuckart, Zool. Untersuch., Theil iii. pp. 3-68. 
1855. Pterotrachea, Untersuch. Pterop. und Heterop., pp. 153, 214. 
1855. „ H. and A. Adams, Gen. Moll., vol. ii. p. 94. 
1856. ,, Troschel, Gebiss d. Schneck., vol. i. p. 44. 
1856. ,, Krohn, Muller’s Archiv f. Anat. Physiol., p. 520. 
1857. ,, Gray, Syst. Arrang. Moll., p. 131. 
1857. Anops, id., op. cit., p. 131. 
1859. Firola, Chenu, Man. Conch., vol. i. p. 123. 
1859. Anops, id., op. cit., p. 123. 
1860. Pterotrachea, Krohn, Beitrage Entwick. Pterop. und Heterop., p. 28. 
1863. Firola, Macdonald, Trans. Roy. Soc. Edin., vol. xxiii. p. 189, pi. ix. fig. 4 (Anatomy). 
1866. Pterotrachea, Keferstein, Bronn’s Thierreich, vol. iii. pt. 2, p. 850. 
1869. „ Boll, Beitrage vergleich. Histiol. Moll., p. 11. 
1871. Firola, Macdonald, Quart. Journ. Micr. Sci. (series 2), vol. xi. p. 274, woodcut (buccal 
teeth). 
1873. Pterotrachea, Weinkauff, Cat. Europ. Meer. Conch., p. 44. 
1875. „ Ranke, Zeitschr. f. wiss. Zool., Suppl. Bd. xxv. p. 77, pi. v. (On the 
Auditory Organ). 
1876. ,, id., Archiv f. mikrosk. Anat., vol. xii. p. 564 (On the Acoustic Organ of 
the Ear). 
1876. ,, Fol, Arch. d. Zool. Exper., vol. v. pp. 105-158 (Development).- 
1877. ,, Edinger, Archiv f. mikrosk. Anat., vol. xiv. p. 171, pi. xi. (Anatomy). 
1883. Firola, Tryon, Struct. Syst. Conch., vol. ii. p. 349. 
1883. Pterotrachea, Fischer, Man. Conch., p. 579. 
1886. ,, Warlomont, Journ. Anat. et Physiol., vol. xxii. pp. 331-343 (Anatomy). 
The determination of the species of the shell-less Heteropods is extremely difficult. 
Many of the forms of Pterotrachea are most unsatisfactorily determined ; some are past 
