406 



ZOOLOGY. 



forming the allantois. The cavity of this sac is continuous 

 with the lumen of the gut. The embryo thus becomes com- 

 pletely surrounded by protective membranes. The cavity 

 between the true amnion and the body w r all (Fig. 205, am. c,) 

 is the amniotic cavity and may be filled with a fluid. 



FIG. 206. 



L'IG. 200. Archecoptcry.r lithographica, an early Reptilian Bird. From Claus. 



Questions on the figure. What in the figure shows this to be a bird? 

 What shows it to be different from typical birds? What is signified by 

 each of the terms in its scientific name? 



FIG. 207. 



FIG. 207. Apteryx anstralis. From Romanes. 



Questions on the figure. What peculiarities does this bird present? 

 What does Apteryx mean? What is the distribution of this species? 

 What are its nearest relatives among the birds? 



