OUDENODON, Bain.
Sp. 0 udenodon fossils on which the above genus and species are founded are from a bluish argillo-ferru ginous limestone in South Africa, and form part of a collection transmitted to the British Museum by A. G. Bain, Esq.
One portion of the fossil skull includes all that part in advance of the temporal fosses ; the fore part of the temporal ridges, at the upper and back part of this fragment, curve as they diverge from each other to the back part of the orbit.. The upper interorbital part of the cranium is nearly flat, with the orbital margins slightly raised, and terminating anteriorly in a low antorbital prominence ; the least breadth of the inter orbital space is one inch. A slight depression divides the antorbital from the supranasal tuberosities. The nasal bones form an almost flat rhomboid surface, from the contracted fore part of which the broad premaxillary part of the upper jaw inclines downward and forward at an open angle. This part is traversed by a low obtuse median ridge, and terminates below in a trenchant edentulous border.
The nostrils are small, oval, and separated from each other by the broad junction of the ascending branch of the pre maxillary with them.
The maxillary bone presents the chief peculiarity, being traversed obliquely by a strong angular ridge, commencing a little anterior to the orbit, and terminating at the alveolar border, not far from the maxillo-premaxillary suture. The
alveolar border gently curves to this termination, and shows no trace of a tooth or alveolus.
The compound structure of the lower jaw is shown at the fractured back part, where an upper (surangular ?) element, thick and rounded above, is received into an outer and lower element, thin above, and thick and bent below, forming a groove for the reception of the upper element. On the outer side of the jaw, about the middle of the part preserved, there is a longitudinal depression or narrow vacuity, above which there is a low ridge. The symphysis is thick, long, and bent up in the form of a beak, terminating by an edentulous sub trenchant border ; its fore and outer part is traversed by a low median ridge. The length of this portion of the skull is 6 inches ; its breadth across the maxillary ridges is 2 inches 10 lines ; the extent of the symphysis of the lower jaw is 2 inches 6 lines. Oudcnodon is more closely allied to the African bidental reptiles of the following order than to the English Rhynchosaurus : so closely, in the construction of the skull, as to suggest the surmise that the absence of the two upper teeth may be a sexual character.