Volume 1

Monograph on the fossil reptilia of the London clay / by Professor Owen and Professor Bell.

  • Owen, Richard, 1804-1892.
Date:
1849
Catalogue details

Licence: Public Domain Mark

Credit: Monograph on the fossil reptilia of the London clay / by Professor Owen and Professor Bell. Source: Wellcome Collection.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

    32/360 (page 16)
    has been established, remains of the Chelone breviceps are preserved in the Hunterian Museum, and in that of my esteemed friend and coadjutor, Professor Bell, S.R.S. I know no other locality of the species than that of Shcppey, in Kent. Chelone longiceps. Owen. Tab. HI, IV, and V. Proceedings of Geological Society of London, December 1, 1841, p. 5/2. Report on British Fossil Reptilia, Trans. British Association, 1841, p. 1/7. The second species of Chelone, from the Eocene clay at Shcppey, which I originally recognised and defined by the fossil skull. Tab. HI, differs more from those of existing Chelones by the regular tapering of that part into a ])rolonged pointed muzzle, than does the Chelone breviceps by its short and anteriorly-truncated cranium. The surface of the cranial bones is smoother than in the Chel. breviceps; whilst their proportions and relations })rove the marine character of the present fossil as strongly as in that species. The orbits (Tab. HI, figs. 1 and 2, o,) are large; the temporal fossm (ib. fig. 3, t,) are covered principally by the posterior frontals (fig. 2, 12); and the osseous shield completed by the parictals (7), and mastoids (s), overhangs the tympanic (28), ex- occipital (2), and paroccipital (4) bones. The compressed spine (3) of the occiput is the only part that projects further backwards. The palatal and nasal regions of the skull afford further evidence of the affinities of the present Sheppey Chelonite to the true turtles. The bony palate (fig. 3) presents, in an exaggerated degree, the great extent from the intermaxillary bones to the posterior nasal aperture which characterises the genus Chelone ; and it is not perforated, as in the soft turtles {Trionyx), by an anterior palatal foramen. The extent of the bony palate is relatively greater than in the Chelone mydas, and the trenchant alveolar ridge is less deep; the groove for the reception of that of the lower jaw is shallower than in the Chelone mydas, or the extinct Chel. breviceps, arising from the absence of the internal alveolar ridge, in which respect the Chel. lonyieeps resembles the Chel. caretta. The Chelone lonyieeps is distinguished from all known existing Chelones by the proximity of the palatal vomer (13, fig. 3), to the basisphenoid (5), and by the depth of the groove of the pterygoid bones (24), and in both these characters in a still greater degree from the Trionyxes; to which, however, it approaches in the elongated and pointed form of the muzzle, and the trenchant character of the alveolar margin of the jaws. The following are dimensions of the skull described : Length of the skull Breadth of ditto across the zygomata Antero-posterior diameter of orbit . Inches. Lines. 4 0 2 6 1 2