CRETACEOUS PTERODACTYLES. 443 



produced; the body of the vertebra is narrower, but deeper, than in the more 

 advanced vertebra (fig. 1). The posterior zygapophysis is surmounted by a 

 tubercle. 



Caudal Vertebrae (PI. 12, figs. 13—16). 



The caudal vertebra, from the anterior half of the tail (figs. 13 and 14), presents 

 a size corresponding with the proportions of the Pterodactyle given by the above- 

 described neck-vertebrte ; the neural arch and zygapophyses continue to be dis- 

 tinctly developed at this region of the tail. There is a foramen (o), leading into 

 the substance of the neural arch, on each side of the back part of that arch, and 

 near the corresponding outlet of the neural canal. In the more distal vertebrae 

 (figs. 15 and 16) the nem*al arch has sunk, and seems almost blended indistin- 

 guishably with the centrum, which is not longer than in the vertebrae nearer the 

 trunk. The zygapophyses cease to be developed ; but the articular, shallow 

 cup and ball at the ends of the vertebrae show that the tail retained its 

 mobility, and was not stiffened or anchylosed as at the corresponding part in 

 UamphorJii/nchus. 



The Sternum (PI. 12, figs. 7—12). 



According to the very able and instructive summary, by Herman v. Meyer, of 

 the osteology of the best-preserved examples of the skeletons of Pterodactyles, those, 

 viz. from the lithographic slates of the Jurassic (Mid-oolitic) series of rocks, the 

 sternum is a compound bone, consisting chiefly of a symmetrical, keelless, broad 

 plate,* having an anterior process answering to the episternal process in the 

 crocodile, t and with distinct side parts, having articulations for a few bony, 

 sternal ribs.;}: As to its resemblance, otherwise, to the sternum of mammals, birds, 

 or reptiles, in regard to the articular surfaces for the scapular arch, nothing has 

 been, hitherto, determined. 



* "Das Brustbein ist ein schwach gewolbtes knochernes Schild, das breiter als lang, und dalier elier 

 dem Briistbein der nur kiimmerlich mit Fluyeln versebenen Strauss-artigen Tbiere beider Erdhiiirten, als 

 dem in den Flug-begabten Vogeln zu vergleicben ist. £s zeigt keinen Kiel iider Griitb, und Man konnte 

 daber glauben, das die Stelle zum Ansatz eines kraftigen Flugmuskels fehit, die Pterodactyln keine gute 

 riieger gewesen -wiiren." ('Reptilien aus dem Litbograpbiscben Scbiefer,' fol., 1859, p. I"). 



f " Am Brustbein der Pterodactyln wird ein vorderer Forsatz wabrgenommen, der den Kiel ersetzt und 

 den Brustmuskeln als Anbeftungsstelle gedient baben wird. Dieser Tbeil erinnert au den Forsatz am 

 Brustbein des Crocodils." (Ibid., p. 18.) 



X " Bei Ramphortnjnehus Gemmingi faud icb ausser den gewobulicben Brustbein nach eine Platte mit 

 Brustrippe welcbe die Verbindung mit den Kiickenrippen unterbalten baben werden und wie in den 

 Vogeln knocbern waren." (Ibid., p. 18, tab. x, fig. 1.) 



