The Descent of Man

ally supposed to have been derived from the
Implacentata or Marsupials; not, however, from
forms closely resembling the existing Marsupials,
but from their early progenitors. The Monotremata
are plainly allied to the Marsupials,
forming a third and still lower division in the
great mammalian series. They are represented
at the present day solely by the Ornithorhynchus
and Echidna; and these two forms may be
safely considered as relics of a much larger
group, representatives of which have been preserved
in Australia through some favourable
concurrence of circumstances. The Monotremata
are eminently interesting, as leading in several
important points of structure towards the
class of reptiles.
In attempting to trace the genealogy of the
Mammalia, and therefore of man, lower down
in the series, we become involved in greater
and greater obscurity; but as a most capable
judge, Mr. Parker, has remarked, we have good