AS TO SOL/NBNESS. 



59 



structure, take place simultaneously, and spread over a 

 considerable time. I have before showTi that f/ie line of 

 direction of weight is through the long axis of the pha- 

 langeal bones, and we find that this comes out at the 

 point of the frog. For purposes of illustration to-day 

 we take two sections of the foot — both vertical sections, 

 but one from before backwards, exactly through the 

 centre {see Fig. 3'), and the second from side to side, 



Fig. 3. 

 through the long axis of the phalangeal bones, coming 

 out at the point of the frog using the anterior section 

 [see diag. 2, fig. 3). In the first section we get sym- 

 metrical halves ; but the section of the cofiin bone will 

 mislead you if you do not remember its wings, which you 

 do not see, but which extend much further back than 

 the surface of the same bone which is open to view. 



The anterior part of the second section of the foot 

 shows the coffin bone resting upon an arch. This arch 

 is formed of the bottom part of the wall of the foot, on 



