'''Monotremes''' are a small [[relict]] group of primitive [[Australasia]]n mammals, consisting of the duck-billed [[platypus]] and the several [[echidna]]s.
In addition to their unusual physical conformations, Monotremes are remarkable for being the only mammals to lay eggs, and to have poison glands (spurs on the back legs of the male platypus); these were an unpleasant surprise for several early zoologists. Another primitive feature is the absence of well-developed [[mammary glandglands]]s, the young platypi and echidnae being nourished by nutritious emissions from their mothers unmodified [[sweat gland]]s.
[[Category:Mammals]]