CRETACEOUS FORMATIONS. 7 



same pit of the Upper Green-sand deposit near Cambridge. The condyloid ball 

 (fig. 12, c ) neatly fits the cup c of fig. 14, and most probably belonged to the 

 same individual. All the characters described and figured in my paper on 

 the ' Vertebrae of Pterosauria,' * and in a preceding monograph,! are repeated 

 in the present larger specimens of the first and second neck-vertebrae. In the 

 more transverse extension of the posterior articular ball of the axis (fig. 16, b) 

 the present specimen agrees with the smaller of the two previously figured 

 specimens of this part of the vertebral column.! 



Cervical Vertebra (Tab. II, figs. 1, 2, and 4). 



The middle (fourth or fifth?) cervical vertebra of a Pterodactyle, corresponding 

 in bulk with that indicated by the fossils above described and figured (Tab. I, 

 figs. 1 — 16; Tab. II, fig- 3), agrees in the proportions of length and breadth more 

 with the smaller vertebrae (Tab. II, figs. 14 — 17, vol. for 1857) than with the 

 vertebrae (ib., figs. 7 — 11) described in my former monograph of that date. It 

 shows the same posterior extension of the centrum (fig. 2, b, p) beyond the neural 

 arch (n), but with somewhat greater divarication of the hinder processes (p) than 

 in figs. 18 or 11 of Tab. II of the above-cited monograph. The present specimen 

 very strikingly illustrates the characteristic breadth and depression of the 

 centrum of the middle cervicals of the large Green-sand Pterodactyles. The 

 neural canal (fig. 2, n ) appears to be proportionally more contracted than in 

 the smaller cervical vertebras; it is relatively much smaller than in any bird, 

 marking well the reptilian nature of the extinct flying air-breather. The anterior 

 surface of the diapophysial productions of the forepart of the base of the neural 

 arch is marked by a groove extending from above and within outwards and 

 downwards. The whole base of the arch has coalesced with the centrum ; the 

 major part, with the neural spine and zygapophyses, has been broken away. 



An oblique side view of the last cervical vertebra of a similar-sized Ptero- 

 dactyle is given in Tab. II, fig. 4, showing the more produced diapophysis (</), 

 perforated by the vertebrarterial foramen (/), indicative of the development in 

 this vertebral segment of a rudimental rib, and of its coalescence with the other 

 elements, the whole extending below the level of the under part of the centrum. 

 Above and behind this foramen is that for the admission of air into the bone; it 

 is of a similar size, and of a narrow, elliptical form. The posterior zygapophysis 

 00 is now raised to a higher level than the anterior one, indicating the sudden 

 bend of the neck at this part. The posterior processes Q>) are smaller and less 



* ■ Philosophical Transactions,' 1859, p. 165, pi. 10, figs. 28—34. 



t ' Palceontographical Society,' vol. for 1S57, pp. 7, 8. 



X Compare Tab. I, fig. 16, with Tab. II, fig. 14, and Tab. IV, fig. 2, of the ' Monograph ' of 1S57. 



