The name scaly anteater is applied to the pangolin; the banded anteater (Myrmecobius fasciatus) is a marsupial, and the spiny anteater (Echidna) is one of the monotremes (see Marsupialia and Monotremata).
Most of the earliest known mammals appear to be related to the Marsupialia and Insectivora.
There are two orders, the Marsupialia and the Monotremata, which do not possess this organ; both these are found in Australia, to which region indeed they are not absolutely confined.
In elevating the marsupials to the rank of a sub-class the name Metatheria has been suggested as the title for the higher grade, with Marsupialia as the designation for the single order by which they are now represented.
We are dependent upon the Carnivora, Rodentia, Ungulata and Marsupialia for our supplies of furs, the first two classes being by far of the greatest importance.
It is, however, less liable to cause confusion, and in many other ways more convenient to employ the better known term Marsupialia in both senses.
Near affinity; and while more nearly related to the Marsupialia (q.v.), in which an imperfect allantoic placenta is sometimes developed, it is broadly distinguished therefrom by the invariable presence of a functional placenta by the aid of which the foetus is nourished throughout the greater portion of intra-uterine life.