TWINNING IN DASYPUS NOVEMCINCTUS 45 



Trager, while the thin-walled part of the trophoblast 

 is known as the diplo trophoblast (dtr). 



TrCi 

 trpi 



Fig, 12, — Au armadillo egg (stage V) attached by the Trager to 

 uterus, and shown as if torn away at Tra. The ectoderm {ec) is a 

 hollow vesicle. The apical pole is at X. Endoderm {en) joins diplo- 

 trophoblast {dtr) in a ring {r). The trophoderm plate {tr pi) lies within 

 the Trager collar {Tra); ectodermal layer of amnion {cc am)', amniotic 

 cavity {ante); mesoderm {ms); much enlarged extra-embryonic cavity 

 {exc). (Modified from Patterson.) 



Stage V. The period of rapid growth and the estab- 

 lishment 0/ bilaterality (Fig. 12). — During the earlier 



