Placentalia (Monodelphia, q.v.; or Eutheria).
" single uterus," - in allusion to the fusion of at least the basal portions of this organ, and in contradistinction to their duality in the Didelphia, or Marsupialia), Cuvier's name for the group which includes all the orders of mammals (See MAMMALIA) except the Marsupialia and Monotremata; other titles for this group being Placentalia and Eutheria.
These three classes are the Monotremata (or Prototheria), the Marsupialia (Didelphia, or Metatheria), and the Placentalia (Monodelphia, or Eutheria); the distinctive characters of each being given in separate articles (see Mono Tremata, Marsupialia and Monodelphia.) The existing monotremes and marsupials are each represented only by a single order; but the placentals are divided into the following ordinal and subordinal groups, those which are extinct being marked with an asterisk (*) i.