A monotreme (Order Monotremeta) is an egg laying mammal.
The Audubon Society calls these animals “the most remarkable of all living mammals…”. The name comes from the fact that they have a single all-purpose ventral opening for both liquid and solid waste disposal, sexual intercourse and, in females, birth. All the more remarkable is that birth takes place in the form of small rubbery eggs.
There are only two Families in the Order:
- The Echidna or Spiny Anteater (Tachyglossidae) which is split into two living genera – Tachyglossus setosus, which inhabits most of the mainland of Australia and the islands to its north, (New Guinea) and south, (Tasmania) and Zaglossus, species of which are limited to New Guinea.
- The Platypus or Duckbill (Ornithorhynchus anatinus) which inhabits the wetter forested parts of the eastern third of the continent of Australia, including Tasmania.
Monotremes were completely unknown to Europeans until the late 18th – early 19th centuries
Reference:The Audubon Society Encyclopedia of Animal Life. 1982 p25