Implacentalia
Im`pla`cen`ta´li`a
| n. pl. | 1. | (Zool.) A primary division of the Mammalia, including the monotremes and marsupials, in which no placenta is formed. |
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
| n. pl. | 1. | (Zool.) A primary division of the Mammalia, including the monotremes and marsupials, in which no placenta is formed. |