174 DE. A. s. WOODWARD OK EXTINCT [Mar. 5, 



anterior margin, bat is nearly complete at its overlapping hinder 

 border. It evidently consists of three pairs of scutes hrmly fused 

 together, their hues of union on the outer face being marked by 

 slight longitudinal grooves. As seen in end view (fig. 2), the ring 

 is only very slightly wider than deep, and its form is rather hexa- 

 gonalthan cylindrical. The lower pair of scutes constitutes the 

 flattened base of the ring, and curves upwards on either side to 

 form the lower margin of the lateral face. Each of the lateral 

 pairs of scutes tapers backwards into a blunt triangular prominence, 

 which reaches very slightly beyond its hinder, overlapping facette. 

 The upper scutes, forming the roof of the ring, are produced back- 

 wards and upwards into a divergent pair of antero-posteriorly 

 compressed, pyramidal bosses, which project considerably above 

 and behind their overlapping facette. Externally (fig. 2 a), all 

 these scutes are quite smooth ; internally, they do not exhibit any 

 trace of contact or connection with the endoskeleton. As already 

 mentioned, the microscopic structure of the bony tissue seems to 

 have been destroyed. 



Part of a second caudal ring, of similar type, was discovered 

 along with the imperfect skeleton in 1899. 



Generic and Specific Determination. 



If the South American fossil skull and mandible now described 

 be compared with the corresponding parts of the type species of 

 Miolania, M. platyceps., from Lord Howe's Island, a reinarkable 

 resemblance in all essential features is observable. The skull of 

 M. platyceps is nearly similar in shape, with its temporal fossae 

 completely roofed by bone, and its external contour modified by 

 the fusion of dermal, bony bosses wnth several of its elements. 

 It exhibits the same broad plate of bone on the cheek behind the 

 tympanic cavity, a precisely similar palate, and the complete 

 laminar septum between the nasal chamber and the orbit. More- 

 over, the nasal bones in M. platyceps scarcely project farther 

 forwards than the premaxillae. Several minor differences, however, 

 may be noted. In M. platyceps all the bosses are relatively much 

 smaller than in the new fossil. The occipital pair are two well- 

 separated small thick bosses, apparently solid and connected with 

 the postero-lateral "horns," The latter are ovoid or rounded in 

 section, turned upwards as much as outwards, and considerably 

 smaller in two of the specimens described and figured by Owen ' 

 than in a third specimen ^, which has also been described by Huxley 

 under the name of CeratocJielys sthenurus ^. Except the inter- 

 parietal, all the bosses seen in the South American specimen also 

 appear to have slight representatives in 31. p>latyceps ; but the latter 

 exhibits an additional small prominence antero-inferiorly at the 



1 Phil. Trans. 1888 B, pis. xxsi.-xxxiv. 



2 Phil. Trans. 1886, pi. xxs. 



3 T. H. Hiixley, " Preliminary Note on the Fossil Eemains of a Cholonian 

 Eeptile, CeratocJielys sthenurus, from Lord Howe's Island, Australia," Proc. 

 Eoy. Soc. vol. xlii. (1887), pp. 232-238. 



