THE ANATOMY OF THE DOG. 415 



witli the middle phalanx, so that when the flexor pro- 

 fundus digitorum is not ia action, the ungual phalanx is 

 pulled back upon the middle phalanx, and the claw which it 

 bears is retracted into an integumentary sheath. 



The olfactory lobes are usually large and the cerebral 

 hemispheres elongated. 



As the Dog (Canis familiaris) 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-lambar ver- 

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

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

 atlas has broad and roimded alae, the anterior margins 

 of which are deeply excavated near the roots. The pos- 

 terior edge of the spinous process of the axis vertebra is 

 almost perpendicular and very thick. 



Nine pairs of ribs are usually connected by sterno-costal 

 cartilages with the sternum, which is composed of eight 

 laterally-compressed sternebrae. Only two of the three 

 ankylosed 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 backwards. The sagittal and lambdoidal crests 

 are greatly developed and meet in a prominent occipital 

 spine ; the zygomata are very wide and arched outwards ; 

 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 swpra-angular process 

 projects ovitwards from the ascending portion of the ramus, 

 and takes the place of the proper angle. The articular 

 condyle is much elongated transversely, narrow and convex 

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

 cesses of the squamosal are produced downwards so as to 

 convert the joint into a complete ginglymus and to restrict 



