LIASSIC FORMATIONS. 



71 



exceeded the sacral formula prevailing in existing Crocod'dia and Laccrtilia, we should 

 gain no firm ground therefrom for predicating Avian aifinity or for building thereon a 

 derivative hypothesis of the class of Birds. Many existing Chelonian Reptiles have a 

 sacrum composed of more than two vertebrae.^ 



The perfect specimen of tail-vertebrae and associated bone-tendons in the specimen 

 (PI. XIX, fig. 4) completes satisfactorily the restoration of this part of the vertebral 

 colunui in Bimorphodon. Before the discovery of Uhamphorhynclius, the order Pferosauria 

 was known only through species having the tail very short. Not only were the vertebrae 

 comparatively few, estimated at twelve or thirteen in Pterodacfj/I/is longirodris^ at 

 fourteen in Pt. spedabilis, at fifteen in Pt. scolopaciceps,^ and as low as ten in Pt. 

 Meycri^ but they were very small and short. The great advocate of the Avian affinity 

 of the Pterosaurs, Soemmkrring, based his chief argument in this character. But 

 CuviER was able to adduce instances of Piptilia with tails as short ; and he might now 

 have cited a Bird with a tail-skeleton as long, as slender, and as many-jointed as in divers 

 Saurians.'' The earliest indication of a range of variety in this part of the bony frame- 

 work of a Pterosaur was deduced, with his usual sagacity, by Buckland. 



In the original specimen of D'nnorpliodon are three caudal vertebrae at the base of the 

 tail, marked K, in pi. xxvii of his jMemoir, from the size of which vertebrae, together with 

 the larger and longer legs, as compared with Plerodactylm lonyirostris, Buckland 

 inferred that the entire " tail was probably longer, and may have co-operated with the 

 legs in expanding the membrane for fiight." *^ " A long and powerful tail," he proceeds 

 to remark, " is in strict conformity with the character of a Lizard" (ib.).'' 



Buckland would have had further direct confirmation of the length and strength of the 

 tail of his Lias Pterosaur, if he had recognised the series preserved at a, a, in his pi. xxvii, 

 as caudal vertebrae ; but they were conceived to belong to the neck, notwithstanding 

 their slenderness and length, and that around them were " small cylindrical bony 

 tendons, resembling the soft tendons that run parallel to the vertebrae in the tails of 

 Rats."** When the evidences of caudal structure were first recognised by Von Meyer, in 

 PliamphorhuncliHS Gemmiv(ji, he detected the homologous structures in pi. xxvii of 



1 'Anat. of Vertebrates,' vol. i, p. 6.5. 



2 By Cuvier, vol. cit., p. 368. 

 ' Von Meyer, op. cit., p. 17. 

 * lb., p. 17. 



^ Owen "On the Archeeopteryx,^'' ' Pliilos. Trans.,' 1S63, p. 33, pis. i — iv. 



« Buckland, loc. cit., p. 221. 

 Archceopteryx had not then been discovered ; else, it might have been objected to the above hint of 

 affinity, not only that there had been short-tailed Pterodactyles, but also long-tailed Birds. 



8 " Mr. Clift and Mr. Broderip have discovered that the remaining cervical vertebrae arc surrounded 

 with small cylindrical bony tendons of the size of a thread. These run parallel to the vertcbrsc, like the 

 tendons that surround the tails of rats, and resemble the bony tendons that run along the back of the pigmy 

 musk and of many birds" (loc. cit., p. 218). 



