Volume 9

Monograph on the fossil Reptilia of the Wealden and Purbeck formations : supplement.

  • Owen, Richard, 1804-1892.
Catalogue details

Licence: Public Domain Mark

Credit: Monograph on the fossil Reptilia of the Wealden and Purbeck formations : supplement. Source: Wellcome Collection.

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    by the same character resembled Petrosuchus, but the differentia] characters were such as could not have been obliterated by growth or age. A third form of Crocodilian made a nearer approach (PI. I, fig. 2) to the average size of the broad-faced genera, corresponded in size with the subject of fig. 2, but offered it could be legitimately removed from the genus Goniopholis. description of this small but well-marked species. Goniopholis, Owen} Species—Goniopholis tenuidens. Plate I, fig. 1. The dental character of the Amphicoelian genus Goniopholis consists of the numerous close-set, fine, longitudinal ridges of the enamel, two of which, larger and sharper than the rest, traverse opposite sides of the tooth from the base to the apex of the crown, midway between the convex and concave lines of the curvature of the tooth, that is, at the fore and back parts of the crown.® The general shape and proportions of the tooth-crowns indicate distinctions of species of Goniopholis. The type of the genus is characterised by the thickness and subcircular section of the crown, and the obtuseness of that in the posterior teeth.® In Goniopholis simus^ the proportion of breadth to length of crown is less than in G. crassidens, and this difference is more marked in the specimen from the Feather- bed of Purbeck which forms the subject of fig. 1, PI. I. This specimen consists of the chief part of the dentary and co-articulated splenial elements of both rami of the same mandible, partially dislocated at the symphysis. The alveolar tract includes the incisive (^■) and molary {m) convexities, without an intervening laniary rising. The incisive convexity includes five sockets, a tooth being retained in the first, third, and fourth on the right, and in the first and third sockets on the left dentary. The foremost tooth has a crown of 6 mm. length and barely 2 mm. of basal breath; each has partially emerged from a socket larger than itself, and exhibits a portion of a tooth in succession to one which has been lost or shed. The socket is separated by an interval of 2 mm. from the second. This shows a subcircular aperture of 5 mm. in diameter. The third socket opens at 2 mm. distance from the second. The tooth (5) in the right dentary shows the inner, longitudinally concave side of the crown, with a basal breadth of 6 mm. ^ ‘Reports of the British Association,’ 8vo., 1841, “On British Fossil Reptiles,” part ii, 1841, p. 690. 2 Loc. cit., pp. 69, 70. ^ ‘Supplement (No. viii) to the Monograph on the Fossil Reptilia of the Wealden and Purbeck Formations,’ Palaeontographical Volume for the year 1878, p. 1, pi. i, 6g. 7. * Ib. Ib., p. 7, pi. V. in one of the species A fourth (ib., fig. 1) no character by which I commence with the