The discovery of an Ammonite (Oppelia subradiata, Sow., from Dundry, now in the British Museum) with the Aptychus in situ closing the orifice, would seem sufficient to set all doubts at rest as to the true nature of that body, viz. that of an operculum. Many of the writers on the continent, however, have not seen that specimen, which unfortunately is unique, and are inclined to attribute to the Aptychus other offices, because:—
page 454 note 1 “ …inhaving the shorter toe of the hind foot projecting at a right angle to the line of the mid-toe”. Miall considers this feature common to other orders of reptiles.
page 454 note 2 See article by DrWoodward, S. P., F.G.S., “On an Ammonite with an Operculuminsitu”. “The Geologist”, 1860, Vol. III. p. 328CrossRefGoogle Scholar (with a woodcut); also DrWoodward, II., F.E.S., GEOL. MAG. 1885, p. 346Google Scholar, and “Student”, vol. iv. p. 1Google Scholar, pl. i. fig. 12.
page 455 note 1 Steinmann, , Berich. uaturforsch. Gesell., Freiberg, vol. iv. pt. 3, 1889.Google Scholar
page 455 note 2 Von Zittel, Handbuch der Pal”ontologie: Cephalopoda.
page 455 note 3 Jahrbuch, Neues, 1881, pt. i. p. 80.Google Scholar
page 455 note 4 Gattung, Harpoceras, Neues Jahrbuch, 1885, pt. iii. p. 596.Google Scholar
page 456 note 1 Atti. Soc. Toscan. di Sci. nat. 1876, vol. ii.Google Scholar
page 457 note 1 Sitz. ber. d. k. Ak. d. Wiss., Math.-nat. cl. Bd. Ixxvi. 1877, p. 329Google Scholar; also, Verhandl, . d. k.k. geol. Reichsanst., Wien, 1879, no. 9, p. 186.Google Scholar
page 457 note 2 Presidential Address, Geol. Soc, 1879, p. 30.
page 458 note 1 Nova Acta Ac. Leop. Car. Nat. Cur., Bd. xv. No. 2, 1831; mentions a “starkst in kende Geruch” when the Aptychus is dissolved in acid.Google Scholar