OCR Text |
Show 718 MR. W. SAVILLE-KENT ON THE [Nov. 19, noted the remarkable resemblance their gait presented to that of a running hen. This recognized avian-like ambulatory deportment of Chlamydosaurus is of special interest with reference to the very generally accepted anticipation that the birds are modified descendants of a reptilian archetype. The temptation in this association is naturally also very great to institute comparisons between, and to suggest affinities with, the Mesozoic Dinosauria, among the majority of which extinct reptilia a bipedal method of progression constituted, there is every reason for believing, a characteristic feature. The very' circumstance, indeed, that the Australasian region, inclusive of N e w Zealand, produces an existing Lizard with such ancient affinities as Hatteria, and the Australian Continent a living freshwater fish, Ceratodus, most abundantly represented in the Triassic and Oolitic formations, as also a number of mammalia and other organic types elsewhere extinct, it might certainly be reasonably anticipated that a Lizard with Dinosaurian affinities, if existing anywhere at the present day, might be sought for with the greatest prospect of success upon Australian territory. A n examination of the skeleton of Chlamydosaurus does not, certainly, as hopefully anticipated, yield indications of that modification of the pelvic elements which is so characteristic of the most specialized Dinosauria; nor, indeed, any salient features that serve to distinguish it amongst the Lacertilia from the skeletons of the ordinary Agamidae. It would seem imprudent under these circumstances to institute other than comparisons of mere accidental and independently arrived at analogies between the coincident erect comportments and corresponding external resemblances exhibited by the types under discussion. These resemblances appear, however, with relation to certain types to be sufficiently remarkable as to invite brief notice. The order of the Dinosauria or Ornithoscelida, as at present recognized, embraces very widely divergent forms of Reptilia. Some of them possess distinctly Avian and others Lacertilian affinities, while in a third group the modification is in the direction of huge brute-like forms emulating or surpassing the Rhinoceros in form and bulk. It is not proposed here to institute comparisons between Chlami/closaurus and such Dinosaurian types as Iguanodon, with its three-toed bird-like feet and ponderous trailing tail, or with the colossal Rhinoceros-headed Triceratops of Marsh and its allies. Within the Lacertilian section of the Dinosaurs there are, however, several described types between which and the Australian Chlamydosaurus there is by no means such a wide gulf fixed. Notably among these, reference may be made to the Anchisaurus colurus of Marsh, of which a figure and description are given in tbe ' Geological Magazine,' dec. iii. vol. x., April 1893. This form is referred to by its describer as representing " one of the most slender and delicate Dinosaurs yet discovered." Its total length did not exceed six feet, and the most remarkable feature possessed by it, as attested by Marsh, and in which respect it " apparentlv |