THE ANATOMY OF THE DOG. 353 



plate of bone rises from its base as a short sheath. An elastic 

 ligament connects the base of the ungual phalanx with the 

 middle phalanx, so that, when ihe flexor profundus digitorum 

 is not in action, the ungual phalanx is pulled back upon the 

 middle phalanx, and the claw which it bears is retracted into 

 an integumentarj' sheath. 



The olfactory lobes are usually large and the cerebral hemi- 

 spheres elongated. 



As the Dog {Canis /amiliaris) is an excellent and easily 

 accessible example of a fissipede carnivore, it may be useful to 

 mention some of the more important points in its anatomy. 



The vertebral column contains twenty dorso-lumbar ver- 

 tebra, of which thirteen are dorsal and seven lumbar, three 

 sacral, and eighteen to twenty-two caudal vertrebrse. The 

 atlas has broad and rounded alae, the anterior margins of 

 which are deeply excavated near the roots. The posterior 

 edge of the spinous process of the axis vertebra is almost per- 

 pendicular and very thick. 



Nine pairs of ribs are usually connected by sterno-costal 

 cartilages vdth the sternum, which is composed of eight lat- 

 erally-compressed stemebrae. Only two of the three anchy- 

 losed sacral vertebrae articulate with the ilia. 



As in the Carnivora in general, the occipital foramen is 

 placed at the posterior end of the skull, and looks almost 

 directly backward. The sagittal and lambdoidal crests are 

 greatly developed and meet in a prominent occipital spine ; 

 the zygomata are very wide and arched outward ; and the 

 coronoid process of the mandible is very large. The size of 

 these parts is in relation to the magnitude of the muscles of 

 the neck and jaws. 



The ramus of the mandible is nearly straight, the proper 

 angle of the jaw being obsolete. A supra-angular process 

 projects outward from the ascending portion of the ramus, 

 and takes the place of the proper angle. The articular 

 condyle is much elongated transverselj', narrow and convex 

 from before backward ; and the pre- and post-glenoidal pro- 

 cesses of the squamosal are produced downvrard so as to 

 convert the joint into a complete ginglymus and to restrict 

 the motion of the jaw to the vertical plane. The supra-orbital 

 processes of the frontals are small and pointed. The root of 

 the alisphenoid is traversed by a longitudinal canal. The tym- 

 panum is bounded below by a convex osseous wall, which is 

 termed the bulla. It opens externally by the short external 



