ON THE FOETAL MEMBRANES OF CHELONIA. 45 



8 dnys old, showing the beginning of the Allantois. A A x2. 



(112.) 



Fig. 21. Posterior tube of the Amnion in four Trionyx embryos 

 13 days old. Slightly enlarged. ("--^ 



Fig. 22. Posterior tube of the Amnion in two Trionyx embryos 

 16 days old. aa x 2. <i6^-) 



Plate. IV. 



Fig. 23. Dorsal view of a Trionyx embryo IOt days old. aax2. 



(157.) 



Fig. 24. Dorsal view of a Trionyx embryo 114 days old, 5^ mm. 



long. Posterior Tube 2 + mm. long. *^"' 



Fig. 25. Trionyx embryo 38 days old, seen from the side of the 



yolk-sac which has however been removed. (^"^•' 



Fig. 26. Trionyx embryo 53 days old. The yolk-sac removed and 



the embryo seen from the ventral or yolk-sac side. x3. 



079.) 



Fig. 27. Trionyx embryo 10^ days old. ^^''^•> 



Fig. 28. Same embryo seen from its dorsal aspect, with the serous 



envelope lifted up, showing the sero-amniotic connection 



and the remnant of the posterior tube of the Amnion. 

 Fig. 29. Cells of the serous envelope in the region of the " placenta " 



in the Clemmys embryo represented in Figs. 71 and 7la. 



DD X 4. 



Plate. V. 



Fig. 30-33. (5-8). Selected transverse sections from the Cleinmys 

 embryo represented in Figs. 2 and 2a. CC x 1. 

 Fig. 30. From the region of the lateral limbs of the Amnion. 



