Morphology. 83 
to understand how he had managed to retain an 
organ which had been renounced by his most recent 
ancestors. Nevertheless, as the anthropoid apes con- 
tinue to present the rudimentary vestiges of a tail 
in a few caudal vertebree below the integuments, we 
might well expect to find a similar state of matters in 
the case of man. And this is just what we do find, as 
a glance at these two comparative illustrations will 
show. (Fig. 15.) Moreover, during embryonic life, 
both of the anthropoid apes and of man, the tail much 
Fic. 16.—Diagrammatic outline of the human embryo when about 
seven weeks old, showing the relations of the limbs and tail to the 
trunk (after Allen Thomson). 7, the radial, and z, the ulnar, border of 
the hand and fore-arm; ¢, the tibial, and f, the fibular, border of the 
foot and lower leg ; az, ear; », spinal cord ; v, umbilical cord ; 4, branchial 
gill-slits ; ¢, tail. 
more closely resembles that of the lower kinds of 
quadrumanous animals from which these higher re- 
presentatives of the group have descended./ For at 
a certain stage of embryonic life the tail, both of apes 
and of human beings, is actually longer than the legs 
(see Fig. 16). And at this stage of development, 
also, the tail admits of being moved by muscles 
which later on dwindle away. Occasionally, however, 
G2 
