154 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 
that of the lower kinds of quadrumanous animals from which these 
higher representatives of the group have descended. For ata certain 
stage of embryonic life the tail, both of apes and of human beings, is 
Fic. 27.—A ppendix vermiformis in orang andin man. JI, ilium; Co, colon; 
C, coecum; W, a window cut in the wall of the coecum; xxx, the appendix. (From 
Romanes.) 
MAN 
FOTAL 
Fic. 28.—The same, showing variation in the orang. (From Romanes.) 
actually longer than the legs (see Fig. 25). And at this stage of 
development, also, the tail admits of being moved by muscles which 
later on dwindle away. Occasionally, however, these muscles persist, 
and are then described by anatomists as abnormalities. The illustra- 
