"I do not doubt that he would say the placentata having single wombs, whilst the marsupiata have double ones, is an instance of this law."
"In the "_Animal Kingdom_" of the great naturalist just named, the marsupiata, or pouched animals, are made to occupy the fourth place among the nine orders of the Mammalia; but should they not rather occupy a place intermediate between the placental mammals and the birds? and does not nature indicate their true position by the position which she assigns to them in the geologic scale?"
"The marsupiata are not oviparous, for their _eggs_ want the enveloping shell or skin; but they, too, are extruded in an exceedingly rudimentary and foetal state, and have to undergo in the pouch a greatly longer period of _incubation_ than that demanded by nature for any bird whatever."