BY JAS. P. HILL. 7^ 



I would lay special emphasis on the fact that the anteriorly 

 directed vaginal portions of the Miillerian ducts remain per- 

 manently imbedded in the tissue of the genital cord, a structural 

 condition ne\er before described for any Marsupial, and confined, 

 so far as our present knowledge goes, to the two allied genera, 

 Perameles and Peragale, though there appears to be a close approxi- 

 mation to a similar condition in M 1/ rmecohius fasciatus. In most 

 other Marsupials, not only do these forwardl}' directed portions of 

 the lateral vaginal canals become entirely free from the genital 

 cord, but in man}^ forms, e.g., Macropods, their backwardly 

 directed portions also become free from the cord over the greater 

 portion of their extent, only their terminal segments retaining 

 their original position in that cord. In concluding for the present 

 this short discussion, I would remark that the facts here briefly 

 set forth, in my opinion, show conclusively that the condition of 

 the genital organs in Macropods — undoubtedly one of the most 

 specialised families of living Marsupials — can in no sense be 

 regarded as primitive, and that just in so far as the genital organs 

 of Perameles depart from the prevalent Marsupial condition they 

 in the same degree realise the more primitive type. Indeed, the 

 urogenital organs of the Peramelidse appear, so far as I am able 

 to judge, to have retained a more archaic condition than those of 

 any other hitherto described Australian ^Marsupial,* a conclusion 

 which I believe gives very material support to that view which 

 regards the existence of an allantoic placenta in the genus 

 Perameles as an extremely primitive feature in its organisation. 



The present work and that to be detailed in succeeding parts 

 of this series of papers has been carried out with the aid of a 



*The condition of the genital organs in the Didelphyidse requires re-examin- 

 ation. In the figures both of Owen (9) and Brass (4) the tissue of the genital 

 cord, which ought developmentally to be found extending between the 

 small median vaginal cul-de-sacs and the sinus urogenitalis, is not shown, 

 hence it is impossible to determine with certainty the relation of the 

 lateral vaginal canals to that tissue, though the bent character of the 

 canals suggests that they are free from it over the greater part of their 

 extent as in Macropods. y^'v\ f^^l^ 



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