MONOTREMES. 



PLATE XV. 



g-laying Mammals : i. Skeleton of Ornithorhynchus anatinus. 2. Skele- 

 ton of Echidna hystrix. 3. Egg of Ornithorhynchus, showing the shape, 

 after St. Hilaire. 4. Young Ornithorhynchus. 5. Head of young Or- 

 nithorhynchus. 5. Mammary gland, pouch, and young of Echidna hys- 

 trix. 7. Apertures of mammary gland of Ornithorhynchus anatinus. 



