PTERODACTYLE» 175 



and teeth with those of Bats (PL 21, and PL 22, MO shows 

 that the fossil animals in question cannot be referred to that 

 family of flying Mammalia. 



The vertebrae of the neck are much elongated, and are 

 six or seven only in number, whereas they vary from nine 

 to twenty-three in birds.* In birds the vertebrae of the 

 back also vary from seven to eleven, whilst in the Ptero- 

 dactyles there are nearly twenty ; the ribs of the Pterodac- 

 tyles are thin and thread-shaped, like those of Lizards, those 

 of birds are flat and broad, with a still broader recurrent 

 apophysis, peculiar to them. In the foot of birds, the meta- 

 tarsal bones are consolidated into one : in the Pterodactyles 

 all the metatarsal bones are distinct ; the bones of the pelvis 

 also difl^er widely from those of a bird, and resemble those 

 of a Lizard; all these points of agreement, with the type of 

 Lizards, and of difl^erence from the character of birds, leave 

 no doubt as to the place in which the Pterodactyles must 

 be ranged, among the Lizards, notwithstanding the approxi- 

 mation which the possession of wings seems to give them to 

 Birds or Bats. 



The number and proportions of the bones in the fingers 

 and toes in the Pterodactyle, require to be examined in some 



air, or become an instrument of true flight, like the arm or wing of Birds 

 and Bats ; the arm or fore leg of tlie Draco volans differs not from that of 

 common Lizards. 



* In one species of Pterodactyle, viz. the P. macronyx, Geo!. Trans. 

 N. s. V. iii. pi. 27, p. page 220, from the lias at Lyme Regis, there is an 

 unusual provision for giving support and movement to a large head at 

 the extremity of a long neck, by the occurrence of bony tendons running 

 parallel to the cervical vertebrae, like the tendons that pass along the back 

 of the Pigmy Musk, (Mosclius pigmsus,) and of many birds. This pro- 

 vision does not occur in any modern Lizards, whose necks are short, and re- 

 quire no such aid to support the head. In the compensation which these 

 tendons afforded for the weakness arising from the elongation of the neck, 

 we have an example of the same mechanism in an extinct order of the most 

 ancient reptiles, which is still applied to strengthen other parts of the verte- 

 bral column, in aftw existing- species of mammalia and birds. 



