THE PERAMELES NASUTA. 
185 
with detail, and the theory of their singular mode of gene- 
ration is still almost entirely conjectural. It has been long 
known that the young of these animals are found in a very 
imperfectly formed state, adhering to the points of the 
mammae, which are always placed in the external pouch, 
and that they remain fixed by their mouth to the nipples, 
till they have acquired a considerable size. Marcgrave, 
Pison, Valentyn, Beverley, and others, supposed the ex- 
ternal sac to be the only uterus, and that the young are 
generated, as well as maintained and suckled, in that cavity. 
Home, Barton, and Blainviile, have maintained, that the 
foetus in utero is not connected with the parent by a pla- 
centa, or umbilical cord; but is suspended loosely in a 
gelatinous matter, like the young of oviparous animals; 
while Geojffroy (Ann. des Sc. Nat. torn, ii.) more recently 
maintains, that the umbilical cord is distinguishable in the 
uterus during the embryo state of the young. Some na- 
turalists, as Blainviile and Desmarest, suppose that the 
young pass, in their embryo state, from the uterus directly 
through the parietes of the abdomen into the external sac ; 
which M. Blainviile thinks is accomplished by means of 
the round ligaments of the uterus {Bull, des Sc. 1818, 
p. 28), whose functions, in other mammalia, have not been 
satisfactorily ascertained: while others believe, that the 
premature young pass from the uterus into the vagina; 
which, by projecting in an inverted state, reaches the ab- 
dominal sac, and deposites them in that cavity, or probably 
even attaches them to the mammas. 
The mode of generation of marsupial animals is con- 
nected with many interesting physiological inquiries ; but 
the opportunities of observation occur so seldom in Europe, 
that the entire and satisfactory solution of this obscure 
problem must be looked for from those who enjoy favour- 
able opportunities in the remote colonies, particularly in 
