MAMMALIA 



211 



ridges on which are placed the openings of the uterine glands. The re- 

 maining Ungulata with diffused placent* do not differ in any important 

 particulars i'rom those already described. 



The polycotyledonary form of placenta is found in the Ruminantia 

 alone. Its essential character consists in the foetal villi not being uni- 

 formly distributed, but collected into patches or cotyledons which form as 

 it were so many small placentae (fig. 157). The foetal villi of these patches 



Fig. 157. Utekus of a Cow in the middle of pregnancy laid open. (From Huxley 



after CoIIil) 

 V. vagina ; U. uterus ; Ch. chorion ; C^. uterine cotyledons ; C^. foetal cotyledons. 



Fig. 158. Cotyledon of a Cow, the fcetal and mateknal parts half separated. 

 (From Huxley after Colin.) 

 u. uterus ; Ch. chorion; C. maternal part of cotyledon; C^. fcetal part. 



14—2 



