424 JAS. P. HILL. 



uot expelled at birth, but absorbed iu situ, it is obvious from 

 the nature of the case there caunot be any shedding of maternal 

 tissue, i. e. no decidua is formed. 



The ease of Perameles is thus in most striking agreement 

 with the condition iu the mole, where, according to the ob- 

 servations of Hubrecht^ (9 and 13), *' no afterbirth is shed, 

 although the animal has a discoid placenta; " and he has 

 further pointed out that " not only is the mole not deciduate, 

 but that even embryonic tissue is left behind against the 

 uterine surface, and is gradually resorbed in situ" (13, 

 p. 117). 



It is thus obvious, as Professor Hubrecht has pointed out to 

 me (in litt.) that the term non-deciduate as long ago used 

 by Huxley is altogether inadequate and misleading as applied 

 to the post-partum conditions obtaining in Talpa and Pera- 

 meles. In these two forms there is not only no complete 

 separation of maternal and embryonic structures at birth 

 (Adeciduata), but no maternal tissue is lost (Deciduata) ; 

 on the contrary, fcetal tissue is actually resorbed by the 

 mother. For such a condition Professor Hubrecht suggests 

 the term Contra-decid uata. 



The discovery of the contra-deciduate character of the 

 placenta of Perameles thus affords welcome testimony to the 

 rightuess of Hubrecht's opinion, based on a consideration of 

 Talpa alone, that this contra-deciduate condition is " not a 

 secondary modification which has arisen among mammals that 

 were already frankly deciduate, but [is], on the contrary, a 

 more primitive developmental phase " (13, p. 118), a view with 

 which I am in complete agreement. 



Possible Vestiges of other Fcetal Membranes. — In 

 connection with the margin of the allantois there are, in some 

 sections, appearances which I can only interpret as greatly 

 altered remnants of the walls of the yolk-sac. These remnants 

 vary very greatly in their detailed relations and in their extent, 



1 Later confirmed by Vernhout (14). 



