578 
PRELIMINARY NOTE ON THE OCCURRENCE OF A 
PLACENTAL CONNECTION IN PERA ME LBS OBE- 
SULA AND ON THE FCETAL MEMBRANES OF 
CERTAIN MACROPODS. 
By Jas P. Hill, Demonstrator of Biology, in the University 
of Sydney. 
(Plate xlix.) 
Some little time ago there came into my hands, through the 
kindness of Mr. A. M. Lea, a female short-nosed Bandicoot, 
Perameles obesula, which proved, on examination, to be pregnant. 
Two embryos were found in the left uterus, and one, the largest 
of the three, in the right. This latter embryo measured 8'75mm. 
from end to end of the curved body. 
On opening the uteri it was found to be impossible to remove 
the emb^os without tearing the foetal membranes, and so two of 
them were preserved enclosed in their membranes and attached 
to portions of the uterine walls. 
Recently I have had the opportunity of examining these 
embryos in some detail, both macroscopically and microscopically 
in serial sections, with the result that a true allantoic placenta 
was discovered. 
The foetal membranes need not be specially considered in this 
note, since they have essentially the same general arrangement 
as those of Phascolarctus and Aepypryrrinus, recently described 
by Prof. R. Semon.* As in these forms the embryo is sunk into 
the yolk sac, and is partially surrounded by the invaginated 
upper portion of the yolk sac wall consisting of splanchnopleure 
(splanchnic mesoderm and entoderm), and distinguished by Semon 
as the "inneres Blatt." This inner leaf does not, however, so 
completely surround the embryo in Perameles as in Macrojyus, 
* Zoologische Forschungsreisen in Australien. Zweiter Band, Erste 
Lieferung. Monotremen und Marsupialier, von R. Semon. 
