490 BRITISH FOSSIL REPTILES. 



(the specimen is marked d in the Plate 27 of his Memoir, loc. cit.), and is described 

 "as the body of a vertebra showing a convex articulating surface, as in the Crocodile" 

 (p. 221). Quenstedt's Pferof/ac^'y/ws .SMew/ra.s showed similar detached dorsals, in one 

 of which it appeared that "the articular surfaces of the body were convex at the back end, 

 and concave at the fore part. "i Ijuckland's specimen serves to dissipate any doubt on the 

 point so important in reference to the Crocodilian affinity. It might be assumed that the 

 Author viewed the convexity as posterior by the expression "as in the Crocodile;" and in 

 the last of the dorso-lumbar series, which I regard, with Buckland, as ' probably lumbar,' 

 in the sense of not being costigerous, the position of " its concave articulating surface '' is 

 demonstrated by those of the articular processes (zygapophyses) at the same end of the 

 vertebra, which prove them to be the anterior pair, slightly prominent, looking upward 

 and inward. Buckland notes these as " two anterior spinous processes, an obvious 

 typographical error for ' ol:)lique ' or ' articular,' venial in one not professedly an 

 anatomist." 



With regard to the Crocodilian atRnity inferred from this structure, it must be remem- 

 bered that the procoelian structure, though it has been observed in Crocodiles from the 

 Greensand of New Jersey,' is characteristic of the Tertiary and existing species, rather 

 than of the order at large, which had more abundant and diversified (amphicoelian and 

 opisthocoelian) representatives in the Secondary ages of Geology. Moreover, the anterior 

 concavity and posterior convexity of the vertebral body obtain in most recent. Tertiary, 

 and Cretaceous Lacertilia ; and finally, the cup- and ball-joints of the centrum appear in 

 the dorsal vertebrae of at least one genus of Birds, though with the ball in front.* 



In the series of nine dorsals, preserved in the subject of PI. 10, d, the centrums 

 slightly lose length as they recede in position from the neck ; the anterior ones measure 

 0009 mm. = 44 lines ; the posterior ones measure O'OOS mm. = 4 lines ; the transverse 

 diameter of the articular ends is 0007 mm. = 3 lines. The dorsal vertebra in Buck- 

 land's specimen presents the same dimensions. These dimensions increase as the two or 

 three anterior dorsals approach the neck, but the greater enlargement of the last cervical 

 is somewhat abrupt. 



For the shape and proportions of the ribs (in the Restoration, PI. 17), I have those 

 marked b, c in the original specimen,^ and the more numerous and better preserved ones 



' " Die Gelenkflaclie der Wirbelkiirper war aiif der Hinterseite convex, wie beim Crokodil, vorn dagegen 

 concav. So scheint es weiiigstens." — Quenstedt, Ueber Pterodactylus sueincus im lithographischen 

 Scbiefer Wiirtembergs. -Ito, 1855, p. 4,5. 



2 Buckland, loc. cit., pi. 27. [This vertebra is shown iu PI. Ill, fig. 2, of the present Mono- 

 graph.] 



3 "Notes on Remains of Fossil Reptiles discovered in the Greensand Formations of New Jersey," 

 ' Quarterly Journal of the Geological Society,' vol. v, 1849, p. 388. 



* As in JptenoiJytes i "On the Vertebral Characters of tlie OrAn Pterosuurin," ' Phil. Trans.,' 1849, 

 pi. X, fig. 22, p. Wi. 



^ Buckland, loc. cit., pi. 27. 



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