1170 FCEIAL MEMBRANES OF CHIROMYS MADAGASCARIENSIS. 



Fig. 2. Foetal CMromys, Spec. A. The chorion lias heen removed, exposing the 

 main sac of the allantois and its accessory lobes on the left side of foetus. 

 The head of the fcetus is towards the lower side of the plate. The main 

 sac has been opened up, exposing the opening of the allantoic canal, into 

 which a white rod has been passed. {Cf, text-fig. 2 and text, p. 1153.) 

 Slightl3' reduced. 



Fig. 3. Foetal CMromys, Spec. A. The same preparation as in fig. 2, but from the 

 right side of foetus. An extensive area of the amnion on the right side 

 of the head of the foetus has been removed. {Cf. text-fig. 3 and text, 

 p. 1155.) Slightly reduced. 



Fig. 4. View of the chorionic sac from the right side of the foetus. Spec. B, show- 

 ing the arrangement and character of the laminar villi. The head of 

 the foetus is towards the left side of the plate. Slightly' reduced. 



Fig. 6. Similar view of the left side of the chorionic sac, Spec. B, to show especially 

 the chorionic appendage which projected as in Spec. A into the right 

 cornu. Slightly reduced. 



Fig. 6. Fcetus, Spec. B, from the right side, after removal from the fcetal mem- 

 branes. The severed umbilical cord is seen overlying the right fore-arm. 

 Slightly reduced. 



Fig. 7. Chorionic appendage. Spec. B, extended so as to show the folded laminar 

 character of the villi of its upper surface. Slightly reduced. 



Fig. 8. Portion of the same, more highly magnified. X about 6. 



Fig. 9. Portion of the exposed surface of the chorionic appendage, Spec. B, showing 

 the convoluted appearance of the villi. X about 6. 



Fig. 10. Enlarged view of the portion of chorion. Spec. B, overlying left side of 

 hinder region of fcetus, showing the folded villi and the non-villous 

 ridged areas. X about 6. 



Fig. 11. (PI. VI). View of the inner surface of allanto-chorion after reflection of 

 the inner wall of allantois (all.iv.), showing the chorionic vesicles 

 {ch.ves.). 



Pig. 12. Section through body of uterus. Spec. B. X about 12. 



Fig. 13. Trans, section through the allanto-chorion in the region of junction of 

 umbilical cord with the inner wall of allantois, showing tl-.ecord {um'b.c.'), 

 the allantoic cavity {all.cav.) crossed bj' two septa {sept.), the allanto- 

 chorion {all.ch.) with its villi and two ciiorionic vesicles (ch.ves.), in the 

 left one of which the opening (op.) is visible. X about 8'5. 



Fig. 14. Section similar to the preceding, more highlymagnified to show the struc- 

 ture of the umbilical cord, allantois, and chorion. X about 12. 



Fig. 15. Section through the allanto-chorion and one of its villi, showing the 

 allantoic entoderm {all.ent.), the connective tissue of the allanto-chorion 

 (all.ch.) prolonged to form the axis of tjje villus (c.t.), in which are seen 

 in section the smaller branches of the allantoic vessels. X about 48. 



Fig. 16. Section through a villous branch, to show the trophoblast (tr.), the under- 

 lyins capillary plexus (cap.), and the connective-tissue core (c.t.). Note 

 the characteristic zone of the latter, below the capillaries (c.t'.). X about 

 360. 



