hi ^pcd m,s.e7a 



71 ch 



Ttvt-rt 



-UTnb.dr 



a-ll 



J. 1078.— Diagrams illustrating the development of the foetal membranes of a Bird. A, earl^' 

 .stage, in the formation of the amnion, sagittal section ; B, slightly later stage, transverse section ; 

 C, stage with completed amnion and commencing allantois ; D, stage in which the allantois has 

 begruii to envelop the embryo and yolk-sac. The ectoderm is represented by ablue, the endoderm by 

 a red line ; the mesoderm is grey. all. allantois ; cdV. the same growing round the embryo and yolk- 

 sae ; am. amnion ; am./., am.f, amniotic fold ; an. anus ; 6r. brain ; ec&l. coelome ; ccel'. extra-em- 

 bryonic coelome ; ht. heart ; m8.ent. mesenteron ; mth. mouth ; nch. notochord ; sp. cd. spinal cord ; 

 flr. m. serous membrane ; umh. d. umbilical duct ; vt. m. vitelline membrane ; n/k, yolk-sac. 



VOL. 11 E E 2* 



