Embryo of Platypus. After Hill and Wilson.

Title: The animals of Australia : animals, reptiles and amphibians
Year: 1909 (1900s)
Authors: Lucas, A. H. S. (Arthur Henry Shakespeare Lucas),1853-1936; Le Souef, W. H. Dudley (William Henry Dudley Le Souef),1856-1923
Subjects: Amphibians; Reptiles; Mammals; Zoology
Source: https://commons.wikimedia.org/wiki/File:The_animals_of_Australia_-_animals,_reptiles_and_amphibians_(1909)_(18194999562).jpg

The platypus or duck-billed platypus (Ornithorhynchus anatinus) is a semiaquatic egg-laying mammal endemic to eastern Australia, including Tasmania. It is one of the extant species of monotremes, the only mammals that lay eggs instead of giving birth.