DEVELOPMENT OF THE SKELETON OF THE TUATAEA. 3 



" the affinities of the Ehynchocephalia to the Chelonians as at least as great as to the 

 Lacertilia ; " while almost the first observation made in the development of the Tuatara 

 was that by Dendy (98, and 99^. p. 66) of the post-amniotic canal, which, though 

 probably of wide occurrence, was originally discovered ^ and is at present known 

 elsewhere only in the Chelonia, and of the horny " shell-breaker," which, being of the 

 Chelonian type ^, places Sphenodon in sharp contrast to the Lacertilia, which, so far 

 as is known, develop a calcified "egg-tooth."^ 



Far reaching as is thus the interest arising from a comparison of the recent Sphenodon 

 with representative members of the living orders of Reptiles, that with certain extinct 

 orders and suborders other than those already alluded to is even more suggestive. 

 The discovery by Credner in the Permian deposits of Saxony of the assemblage of 

 vertebrate forms he has so aptly termed* the " Eotetrapoda," and more particularly the 

 genus he has less aptly named Paleeohatteria, has materially lessened the structural 

 gap between the Reptilia and the Stegocephalia ; while the description by Lortet, eight 

 years ago, of Rhynchocephalian remains ^ from the Upper Jurassic of the Rhone Basin 

 which reveal new cranial cliaracters, with that of Crocodilian resemblances in Champ- 

 sosaurus *^, which, like Acrosaurus '', is believed to have been aquatic in habit, shows 

 the Ehynchocephalian Order, now all but extinct, to have been in the past extensive 

 and subject to considerable modification. It is now generally conceded that the 

 Anomodontia (Theriodontia and Pariasauria) in some respects stand on an even lower 

 structural level than the Rhynchocephalia ; and, this being so, the recognition among 

 these of Ehynchocephalian characters — originally by Seeley in Procolophon in 1878 ^ — 

 only the more fully justifies the belief in the primitive nature of the Ehynchocephalian 



' Mitsukuri, K. : Journ. Sci. Coll. Tokyo, voL iv. 91, p. 10. Cf. also Dendy, 99 ". pp. 251 & 255. 

 = Cf. Dendy, A., 99". pp. 56 & 59, and Parker, W. K., 'Challenger' Reports, Zool. vol. i. pi. 3. fig. 1. 

 ' Cf. Leydig, F. : ' Die in Deutsohl. Icbend. Arten d. Saurier,' Tiibingen, 1872, p. 110 ; and Boulenger, G. A. : 

 on the Ophidian Aipysurus annulahis, in Willey's ' Zoolog. Eesiilts,' Cambridge, 1899, p. 57. 



* Credner, H. : Allgem.-Verhandl. Naturwiss. Abhandlg. Berlin, Hft. xv. 1891, pp. 1-52. 



* Lortet, L. : Archv. Mus. Hist. Nat. Lyon, Bd. v. 1892, pp. 139. It is interesting to note that Sauranodon 

 possessed proeoeloiis vertebrae. 



" Dollo, L. : Bull. Soc. Beige d. Geo!., tome v. 1891, p. 151. 



' AndreiB, A. : Ber. Senckenbg. Naturf. Gesellsoh. 1893, p. 21. 



^ Seeley, H. G. : Quart. Journ. Geol. Soc. vol. xxxiv. 1878, p. 803. The pterjgo- vomerine relationship is 

 now known to be Ehynchocephalian among Anomodonts in Procolophon and Galesaurus (A. S. Woodward, 

 ' Outlines of Vertebr. PaLwnt.,' Camb. 1898, pp. 148 & 152), and it is probably so in Pariasaurus also ((/. 

 Seeley, Phil. Trans, vol. 183 B. 1892, p. 317). The description of a post-palatine fossa, which in all probability 

 received a median tonsil (" bursa pharyngea ") like that observed by Killian (Morph. Jahrb. Bd. xiv. 1888, 

 pp. 659-690) for living reptUes, as the posterior nares, and of the true posterior nares (p. 317) as " anterior 

 comma-shaped palatal vacuities,"' is erroneous. The study of the palatal region of this animal needs re- 

 investigation. 



