1881.] VAGINAL APPARATUS IN THE MACROPODIDiE. 993 



to show, that vphen the median canal is open and young have been 

 born the young has passed through this opening on its way to the 

 exterior, then the fact that this difference should exist among 

 females which have born young — a difference not only in form 

 but also in function — appears most strange. 



With regard to the otiier species the evidence is far more satis- 

 factory. 



Six specimens o{ Macropus rufus have been examined: four of them 

 bad born young, and the median canal was open ; two of them had 

 not born young (one was not full-grown), and the canal was closed. 

 This seems to show that in M. rnfus an opening is formed in the 

 median chamber either during pregnancy or at the time of parturition. 



The two other species of Macropus are isolated examples, and do 

 not throw any additional light on the subject. 



The twenty examples of the genus Halmaturus may be con- 

 sidered together. It will be observed that in one young one (Luca's 

 H. hennetti) and in one adult (brass's H. bennettf) the median canal 

 was found to be closed, and that in all the rest, including two other 

 young ones (Brass's H. bennetti and our H. ualabatus), it was 

 open. This seems to show that in the genus Halmaturus the median 

 canal may become open before the young have arrived at maturity, 

 but that the thin septum which divides it from the urogenital sinus 

 may remain perfect till after maturity is reached. In either case what 

 evidence there is shows that after young have been born the canal 

 is open. 



Our three examples of Petrogale xanthopvs bear out the same 

 idea ; but whether the cul-de-sac is converted into an open canal 

 early (as in some Wallabies), or not till young are about to be born 

 (as in M. rufus), the evidence is not sufficient to decide. 



As to the specimen of Dorcopsis luctuosa and the three of Dendro- 

 lagus inustus, the evidence as to whether young had been born or 

 not is not conclusive. As far as it goes, however, it is in favour of the 

 latter supposition. That the canal would be open when young had 

 been born, however, in the present state of the evidence it would be 

 rash to assert. 



The genus Hypsiprymnus offers a different condition from any we 

 have considered : it had undoubtedly brought forth young ; and as 

 undoubtedly the median canal is closed. So far our specimen agrees 

 with the examples oi Macropus major described by Prof. Owen, and 

 with the " Kangaroo " described by Seller. It differs from the 

 former, however, in the fact that the muscular thickening and con- 

 striction in the lateral canals, which are present in all our other 

 specimens, are here absent. Thus in this case, in which the young 

 passed down the lateral vaginal canals, we find a condition of these 

 canals different from that of any of the other Macropodidae which 

 we have examined. 



The observations on the Kangaroos whose species are not given 

 are in agreement with those already considered. Home's two ex- 

 amples are similar to those of Macropus rufus already described ; but 

 it is not stated whether young had been born. 



Proc. Zool. Soc— 1881, No. LXIV. C4 



