Sir Everard Home on the ova of the Opossum Tribe. 235 
In the kangaroo, the ovum when expelled from the corpus 
luteum, passes along the Fallopian tube, and as there is a 
thickening and glandular structure surrounding the portion 
of the tube next to its termination in the uterus, it is there 
that the yelk, or something analogous to it, is probably 
secreted ; the ovum with the newly acquired yelk, drops from 
a pendulous opening into the uterus, in which it receives the 
albumen. In one specimen the uterus in a pregnant state, 
came under my observation ; but as it was sent from New 
South Wales, in spirit which had not been timely renewed, 
the contents of the uterus were reduced to a confused mass, 
in which only a part of the bones could be made out ; 
enough was however seen, to determine that the ovum of 
the kangaroo in the uterus has an abundant supply of albumen. 
There was no attachment whatever between the albumen 
and the uterus. There are two lateral canals that commu- 
nicate between the uterus and vagina : these answer the pur- 
pose of aerating the foetus by means of atmospheric air. 
As the penis of the male has only one orifice at the point 
adapted to the os tincae, the ovum must of necessity be im- 
pregnated in the uterus, the structure of the Fallopian tubes, 
and their mode of terminating in the uterus, rendering it 
impossible for the semen to pass into them. 
The foetus, as soon as it arrives at a certain size (at which 
time it in general weighs about 1 2 grains,) is expelled from the 
uterus, and is received into the marsupium, where it becomes 
attached to the point of one of the nipples, at first by simple 
contact ; but as the foetus grows, the nipple is found farther 
in the mouth upon the surface of the tongue. In the 85th 
volume of the Philosophical Transactions, Plate XVIII. XIX. 
XX. and XXI. and in the 100th volume, Plate XIII. most of 
