Fig, io 



Fig. II 



Figs, io, ii. — Two eggs of the armadillo, drawn as before, partly 

 overlapping. The upper egg (stage III) shows the ectoderm (ec) round- 

 ing up into a ball and the endoderm (en) in the form of a continuous 

 layer beneath the ectoderm. The apical pole is at -Y. The lower egg 

 (stage IV) shows the ectoderm (ec) rolled into a ball and nearly sur- 

 rounded with endoderm (en). Trophoblast has been thickened into 

 Trager (Tra) at the upper pole and the remainder is called diplotropho- 

 blast (dtr); extra-embryonic cavity (exc). (Modified from Patterson.) 



