Didelphia

from The Collaborative International Dictionary of English v.0.48

Didelphia \Di*del"phi*a\, n. pl. [NL., fr. Gr. ? = ? matrix,
   uterus.] (Zool.)
   The subclass of Mammalia which includes the marsupials. See
   {Marsupialia}.
   [1913 Webster]