284 THE SKELETON OF THE BABBIT. 



however, in the adult so intimately associated with the bones 

 of the jaws that they may conveniently be described with the 

 skeleton. The hairs and claws, which are special develop- 

 ments of the epidermis, or surface-layer of the skin, will be 

 described in the next chapter. 



The rabbit's skeleton may be divided, like that of the dog- 

 fish, into axial and appendicular portions, which will be dealt 

 with successively. 



The following points in the rabbit's skeleton should be 

 noticed as characteristic of. the great majority of mammals, 

 and separating them from lower vertebrates. 



Epiphyses are present at the ends of the vertebral centra, 

 as well as at the ends of the long bones of the limbs ; and the 

 successive vertebree are connected by intervertebral ligaments : 

 the cervical vertebrae are seven in number. The sternum is 

 transversely jointed. In the skull, there is a completely ossi- 

 fied occipital ring, with two condyles : the cranial and olfactory 

 cavities are separated by a bony cribriform plate : there is not 

 a distinct para-sphenoid on the under surface of the skull ; the 

 lower jaw articulates directly with the squamosal : there are 

 three or four small but distinct auditory ossicles. The teeth 

 form a single but discontinuous row round the margin of each 

 jaw. In the shoulder girdle, the coracoid is reduced to a 

 small process of the scapula ; and there is no interqlavicle. 

 The ankle-joint is situated between the tibia and fibula above, 

 and the proximal tarsal bones below : the fourth and fifth 

 carpalia, and the corresponding tarsalia, fuse to form a single 

 bone in each limb : the preaxial digit, corresponding to the 

 thumb, has two phalanges, while the others have each three. 

 In the rabbit the first digit of the hind Umb, corresponding to 

 the great toe in man, is abortive : in other mammals it has 

 two phalanges like the thumb. 



Examine the prepared skeletons and make drawings to 

 scale of the several parts. 



