LIASSIC FORMATIONS. 
71 
exceeded the sacral formula prevailing in existing Crocodilia and Lacertilia, we should 
gain no firm ground therefrom for predicating Avian affinity 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 
(PL XIX, fig. 4) completes satisfactorily the restoration of this part of the vertebral 
column in Dimorphodon. Before the discovery of Bhamphorhynchus, the order Pterosauria 
was known only through species having the tail very short. Not only were the vertebrae 
comparatively few, estimated at twelve or thirteen in Pterodactyliis longirostris^ at 
fourteen in Pt. spectabilis, at fifteen in Pt. scolopaciceps^ and as low as ten in Pt. 
Meyeri^ but they were very small and short. The great advocate of the Avian affinity 
of the Pterosaurs, Soemmerring, based his chief argument in this character. But 
Cuvier was able to adduce instances of Beptilia 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 THmorphodon are three caudal vertebrse at the base of the 
tail, marked K, in pi. xxvii of his Memoir, from the size of which vertebrae, together with 
the larger and longer legs, as compared with Pterodactylus lonyirostris, Buckland 
inferred that the entire “ tail was probably longer, and may have co-operated with the 
legs in expanding the membrane for flight.” ® “ A long and powerful tail,” he proceeds 
to remark, “ is in strict conformity with the character of a Lizard” (ib.).'^ 
Buckland would have had farther direct confirmation of the length and strength of the 
tail of his Lias Pterosaur, if he had recognised the series preserved at a, d, 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 
BliampJiorhyncJius Gemmwyi, he detected the homologous structures in pi. xxvii of 
1 ‘Anat. of Vertebrates,’ vol. i, p. 65. 
2 By Cuvier, vol. cit., p. 368. 
^ Voii Meyer, op. cit., p. 17. 
^ Ib., p. 17. 
5 Ovs'en “On the Archceoptei-yx," ‘Philos. Trans.,’ 1863, p. 33, pis. i— iv. 
6 Buckland, loc. cit., p. 221. 
7 Archaeopteryx 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. 
® “Mr. Clift and Mr. Broderip have discovered that the remaining cervical vertebrae are surrounded 
with small cylindrical bony tendons of the size of a thread. These run parallel to the vertebrae, 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). 
