58 INTRODUCTION. 



Cetacea are said to have only six, and the three-toed Sloth, or Ai,* has 

 nine. Mr. Bell, indeed (see his valuable paper in the Transactions of the 

 Zoological Society, part i., 1834), regards the eighth and ninth vertebrae in 

 this animal as assignable rather to the dorsal than the cervical division of 

 the vertebral column, in consequence of their having a small bony append- 

 age, considered to be a rudimentary rib, attached to an articular surface 

 on each transverse process. The appendages of the eighth vertebra 

 are very minute, being only four-tenths of an inch long ; in the ninth 

 they are six lines in length, and nearly two in breadth. Meckel, who 

 was acquainted with the existence of these appendages in the ninth only, 

 hints at the possibility of this vertebra being dorsal. It is, nevertheless, 

 to be remarked, that the cervical foramen exists in both these supernu- 

 merary vertebrae. 



That the number of the vertebrae of the neck, in all the mammiferous 

 animals, with the above exceptions, should not exceed seven, is very 

 remarkable, when we compare the long neck of the Giraffe with the 

 short neck of the Elephant, or call to mind the contour of the Whale-tribe, 

 where this part forms no distinguishable appearance, but is lost in the 

 unwieldy fish -like figure of the body: but this difference in the length 

 of the neck of Mammalia depends upon the form of the vertebrae, and 

 not upon their number. In the cetaceous animals they are (as 

 before stated) not only very thin, but anchylosed, or ossified together, 

 so as to admit neither of flexion nor of rotatory motion; in the 

 Giraffe, on the contrary, whose pliant neck towers among the foliage of 

 the trees, they are elongated to an extraordinary degree.f This elonga- 

 tion, we need scarcely add, is inconsistent with the support of such a 

 skull as that of the Elephant, with its ponderous tusks, or with the pre- 

 sence of such antlers as load the head of the Wapiti, or the Elk. 



Of the cervical vertebrae, the first two differ materially from the rest, 

 and are exceptions to the general form which obtains among them. 

 The first vertebra, or the atlas (figs. 44, 45, 46, 47, 48), as it is fanci- 

 fully named, consists of an anterior portion, which may be termed its 

 body, and a posterior arch, with tranverse processes, and a small spinous 

 process. On the sides of the ring thus formed, are certain articulating 

 surfaces, answering to the oblique processes of the other vertebrae, namely, 

 two concave, on its superior aspect, into which are fitted the condyles of 

 the occipital bone, and two on its inferior aspect, for the reception of the 



* Meckel found eight cervical vertebrae in a skeleton of the Bradypus Torquatus, in the Paris 

 Museum. See Traite General d' Anatomic Comparee, p. 397 and 430, where reference is also made to 

 the AI. 



t With respect to the cervical vertebrae of the Giraffe, Professor Owen observes, "that they are not only 

 remarkable for their great length, but also, as has been recently shewn by Dr. Blainville, for the ball 

 and socket form of the articulations of their bodies ; the convexity being on the anterior extremity, 

 and the concavity posteriorly, agreeing, in this particular, with the vertebrae of the Camel." Proc 

 Zool. Soc., 1838, p. 21. 



