600 ON THE EARLY STAGES IN THE DEVELOPMENT OP THE EMU. 



Plate XV. 



Figs. 24—28 are a series of sections through the hinder end of a seven 

 days' embryo showing the neurenteric passage, and the relation 

 of the hinder end of the notochord at this stage to the hypoblast 

 of the hind gut. 



Fig. 24. — Section just in front of the neurenteric canal, with separate 

 hind gut (hg.), notochord (n. cli.J, and medullary canal (m.J. 

 7ns. lateral plates of mesoblast. am. amnion. 



Fig. 25. — Section a little further back at a point where the notochord has 

 united with the wall of the hind gut. 



Fig. 26. — Section showing union of wall of hind gut and of medullary 

 canal. 



Figs. 27 and 28. — Sections passing respectively through the anterior and 

 the posterior parts of the neurenteric passage. 



