60 



THE EVOLUTION OF MAN. 



kingdom as a genuine Worm. The difference between it 

 and other genuine Worms cannot have been greater than is 



Fig. 187. — Appendicularia, seen from the left side : m, mouth ; ft, gill. 

 intestine ; o, oesophagus ; v, stomach ; a, anus ; n, nerve-ganglia (uppei 

 throat-knots) ; g, ear-vesicle ; /, ciliated groove under the gill ; h, heart | 

 t, testes j e, ovary ; c, notochord ; s, tail. 



Fig. 188. — Structure of an Ascidian (seen from the left, as in Fig. 153 

 and Fig. 14, Plate XI.) : sb, gill-sac ; v, stomach ; t, large intestine ; c, 

 heart ; t, testes ; vd, seed-duct ; o, ovary j o', matured eggs in the body, 

 cavity. (After Milne Edwards.) 



