163 



gives a "nodding motion" at each step, particularly 

 marked in good walkers. 



A. a^ Puts weight on left hind- foot. 



a'. Increases this joining the ophidian and third 

 SS. 



a\ Puts the iveight on left fore-foot. Raises right 

 fore. 



B. h'^ and b'^ Brings left hind-foot on its in- 

 ner hearing; turns right hind-foot for outer hearing 

 and brings it foriuard. 



h'^. Puts left fore-foot on inner hearing. 



A'. a\ Keleases a^ b'^ 



a^. Keleases a'' b'' at junction of central and third 

 S. Puts down right hind-foot. 



a^. Carries/orirarc? and puts down right fore. 



Thus we have A' a^ right hind foot down. A'^ 

 right fore foot down. We are inchned to think that 

 in \hQ full progress of the step a fore-foot leaves the 

 ground as the opposite fore-foot is put down, thus 

 shghtly differing from the description of von 

 Oeynhausen ; but as this fore-foot, after rising, 

 awaits the movement of the collateral hind-foot, 

 raised and carried forward by the posterior line^ 

 the difference is not important. 



§ 148. Retrogressio7i may be brought about, after 

 the formation of the diagonal oppositions which 



