DEVELOPMENT OF THE SKELETON OF THE TUATARA. 3 
“ the affinities of the Rhynchocephalia to the Chelonians as at least as great as to the 
Lacertilia ; ’ 
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,” * 
* while almost the first observation made in the development of the ‘Tuatara 
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 Paleohatteria, 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 characters, with that of Crocodilian resemblances in Champ- 
sosaurus ®, which, like Acrosaurus7, is believed to have been aquatic in habit, shows 
the Rhynchocephalian 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 Rhynchocephalian characters—originally by Seeley in Procolophon in 1878 5— 
only the more fully justifies the belief in the primitive nature of the Rhynchocephalian 
‘ Mitsukuri, K.: Journ. Sci. Coll. Tokyo, vol. iv, 91, p. 10. Cf. also Dendy, 99°. pp. 251 & 255. 
2 Of. Dendy, A., 99°. pp. 56 & 59, and Parker, W. K., ‘Challenger’ Reports, Zool. vol. i. pl. 3. fig. 1. 
> Of. Leydig, F.: ‘ Die in Deutschl. lebend. Arten d. Saurier,’ Tiibingen, 1872, p. 110; and Boulenger, G. A. : 
on the Ophidian Aipysurus annulatus, in Willey’s ‘ Zoolog. Results,’ Cambridge, 1899, p. 57. 
* Credner, H.: Allgem.-Verhandl. Naturwiss. Abhandlg. Berlin, H{t. xv. 1801, pp. 1-52. 
° Lortet, L.: Archv. Mus. Hist. Nat. Lyon, Bd. v. 1892, pp. 139. It is interesting to note that Suwranodon 
possessed proccelous vertebree. 
® Dollo, L.: Bull. Soc. Belge d. Géol., tome v. 1891, p. 151. 
7 Andrew, A.: Ber. Senckenbg. Naturf. Gesellsch. 1893, p. 21. 
5 Seeley, H. G.: Quart. Journ. Geol. Soe. vol. xxxiv. 1878, p. 803. The pterygo-vomerine relationship is 
now known to be Rhynchocephalian among Anomodonts in Procolophon and Galesaurus (A. $8. Woodward, 
‘ Outlines of Vertebr, Palxont.,’ Camb. 1898, pp. 148 & 152), aud it is probably so in Pariasaurus also (cf. 
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. xiy. 1888, 
pp. 659-690) for living reptiles, as the posterior nares, and of the true posterior nares (p. 317) as “ anterior 
comma-shaped palatal yacuities,” is erroneous, The study of the palatal region of this animal needs re- 
investigation. 
B2 
