206 



Arthur Willey, 



ridges, and crescentic folds. The villosities are flattened from side 

 to side. so that they present a clean-cut appearance with thin free 

 edges. They are much lower on the obplacental surface (correspond- 

 ing with the back oi' the foetus) than at tlie ends and sides of 

 the blastocyst : so that whereas the inferior free surface (i. e. inferior 



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Fig. G. 



Fig. H. 



Fig. G.*) Detached placenta of beaver from above. i. e. froin the maternal aspect. 

 1. Omphalo-mesenteric cord. 2. Omphalo-mesenteric ligament. 3. Amnio-placental 

 iusertion. 4. Umbilico-placental insertion with sinus terminalis. 5. Efferent utero- 

 placeutal vessel. 6. Afferent vttero-placental vessel. 7. Stalk or radix placentae. 

 8. Placenta. 



Fig. H. Semidiagrammatic view of caudal end of blastocyst. 1. Splanchno- 

 pleuric villi. 2. Granulated zone. 3. Umbilico-uterine ligament. 4. Uterine wall. 



*J The symmetrical notch at the front end of the placenta was only conspi- 

 cuous in the particular specimen here figured. 



with relation to the placenta, which is superior) of the blastocyst 

 appears relatively smooth to the unaided eye, the superior herai- 

 sphere appears shaggy. The shagginess is due to the high crescentic 

 villi, which project as much as a millimetre above the surface. They 

 cease abruptly some distance (about the width of 1,5 centimetre) 



