462 PHILOSOPHICAL TRANSACTIONS. [aNNO 16Q8. 



distinct alveolus, or socket in thejaw, and remaining separated some way above 

 the jaw-bone, and only joined at the head. In the under jaw-bone, there 

 were likewise on each side, 4 smaller incisores before ; then a little void space; 

 after that the dens caninus : then 3 larger incisores ; and lastly, 4 drntes mo- 

 lares, answerable to those in the upper-jaw, but somewhat smaller : in all, 48 

 teeth, in both jaws. 



There were 7 vertebrae of the neck; 13 of the back or thorax; 6 of the 

 loins: 3 of the os sacrum ; and 22 of the tail ; in all 31, and all extraordinarily 

 contrived. The first vertebra of the neck, to which the head is fastened, and 

 therefore called the atlas, has two broad transverse processes, but no spine. 

 The 2d vertebra of the neck has a very large and thick spine of a triangular 

 figure ; and in it a large semi-circular sinus, so deep, as to receive into its 

 bosom a great part of the first vertebra ; by which means, the articulation is 

 very much strengthened. This vertebra is called dentata, from the tooth-like 

 protuberance, and which is received into the hollow of the first vertebra, where 

 the medulla spinalis passes. This vertebra has backwards two processu'; obliqui 

 supcriores, and two obliqui inferiores. The 3d vertebra of the neck has the 

 same processes, both before and behind ; but the spine here was about a of an 

 inch in height ; about the 3d part of an inch thick ; and just at the top seemed 

 to be a little cleft. The 4th and the 3th vertebrae had the same processes, as 

 the od vertebra ; and the spine here, likewise very thick, and cleft at the top ; 

 but gradually lessening in height, as also thickness. The 6th vertebra, besides 

 the former processes, had likewise an acute transverse one, on each side ; and 

 its spine much shorter, and more acuminated than the former. The 7th ver- 

 tebra of the neck had only two oblique processes before, and none behind ; and 

 two acute transverse processes, and a very short and sharp spine : so that, on 

 holding up the head, the spine of the first vertebra of the thorax would touch 

 the top of the 5th vertebra of the neck. These vertebrae are so strongly and 

 closely locked into one another, that though each of them are large in itself, 

 yet thus articulated, they do not make full two inches in length. This thick- 

 ness and strength of the vertebrae of the neck, and also of several of the ver- 

 tebrae of the thorax and loins, and the prominent bony ridge in the cranium, 

 do so well secure its neck, back, and head, that should it h.ippen to fall to the 

 ground, there would be no danger of breaking any of them. 



The first 7 vertebrae of the thorax have 2 oblique processes forwards, which 

 run uniler the hinder oblique processes of the preceding vertebra, and have two 

 oblique processes backwards, which ride over those of the succeeding vertebra; 

 as likewise two transverse processes, which at their ends have small acetabulas 

 or sinuses, for receiving the heads of the ribs, which are fastened to them. 

 The spines of these vertebrae, are slender, thin, and shar|) ; about -j- of an 



