266 ZOOLOGY. 



when the young rabbits are born part of the uterine wall 

 is actually torn away with them. This is expressed by 

 saying that the rabbit's placenta is deciduate. Before birth 

 the body- wall is, of course, incomplete ventrally, as in the 

 chick, at the point where it is continuous with the true 

 amnion and where the stalks of the yolk-sac and allantois 

 pass out. The scar of closure at this point persists, even in 

 the adult, as the umbilicus or navel. 



The stalk of the allantois persists as the urinary bladder. 

 When born, the young rabbits are still enclosed in the true 

 amnion. 



