338 



ON PARTURITION IN MARSUPIALS. 



of the digits of the foot. The early initiation of the lip-fusion, 

 leading to the establishment of the sucking mouth, was demon- 

 strated in a series of embryos of IVichosurus, and an interesting 

 comparison was instituted between the recently hatched young of 

 Ornithorhynchus and the new-born Marsupial. 



The remarkable and unique mode of parturition which occurs 

 in certain Marsupials was explained and illustrated by a series of 

 micro-photographs. It was shown that in Perameles, Dasyurus, 

 and Trichosurus the young reach the exterior, not through one or 

 other of the lateral vaginal canals, but by way of a direct median 

 passage, constituted in front by the epithelially lined median 

 vagina and behind by a cleft-like " pseudo- vaginal passage," 

 actually formed at the time of parturition as a tear in the 

 connective tissue situated behind the median, and between the 

 lateral vagina?. The occurrence of the same mode of parturition 

 was demonstrated for Phascolarctos (the fact being recorded here 

 for the first time), and lantern-slides were shown indicating that 

 the same mode of birth also holds good for the Gamba (Didelphys 

 auritct). The bearing of these facts on the patent condition of 

 the median vagina in certain Macropods was briefly discussed. 



