348 DR Di BERRY HART. 



of Milller in an embryo of Macropus rufas, and remark that the 

 arrang-ement of the Miillerian ducts is tlie same as in the adult 

 opossum. 



In my own specimens (fig. 27) the naked-eye arrangement of 

 the organs in one of the rat kangaroos (^Hypsiprymnus) is 

 shown. The following are the measurements : — 



Length of genital tract from ovary to lower end of bowel, 



7 cm. 

 Length of cornua, 7 mm. 

 Diameter of central canal, 5 mm. 

 Diameter of lateral canal, 3'5 mm. 



In the opossum {Didelj^hys dorsigera) we have a double uterus,, 

 two lateral canals, a lower unpaired portion into which the 

 former opens, then the urinogenital sinus. 



In Macropus, figured by Owen, we have two lateral canals : 

 a central blind pouch, with double cornua and ovaries. 



A very important point is the relation of the ureters. These 

 pass inside the lateral canals, and lie outside the median pouch 

 when this is present (fig. 29). In the opossum {Didclphys dorsi- 

 gera), the central portion of the tract is not well marked, and 

 may be only represented by the upper part of the lateral canals 

 where the os uteri of each side opens, or by the lower mesial 

 portion above the urinogenital sinus. In this opossum the 

 ureters lie to the inside of the lateral canals. 



The opinions liitherto expressed on these rem.arkable struc- 

 tures making up the vaginal segment of the genital tract in 

 marsupials have all been to the effect that the lateral canals as 

 well as the central part are Miillerian. 



Tourneu.x and Legay say : " Chex les marsupiaux, la non 

 fusion des conduits de Milller {.DidelpJiys dovHigera) est la con- 

 seijuence d'une disposition speciale des ureteres, qui, an lieu 

 d'embrasser dans leur courbure le cordon genital s'engagent 

 dans I'epaisseur meme de ce cordon, entre les conduits de 

 Mtiller qu'ils separent" {op. cit., p. 376). 



Urass says: " Wir .... von einer dreifachcn Vagina 

 sprechen konnen " (]). oG). 



The conclusion I have come to in regard to the morphology 

 of the vaginal tract in the marsupials is that the lateral canals 



I 



