noon
`` Why do you stop just there , Jim , in the most interesting part ? Please go on and finish -- if you can ! '' cried Dorothy . Mr. Winters also nodded and the boy added : `` This was the riddle : What animal in the morning walks on four feet , at noon on two , and at evening on three ? '' `` At it , youngsters , at it ! Cudgel your brains for the answer . We do n't want any mixed-anatomy Sphinxes rampaging around here , '' urged the farrier .