20 GUIDE TO THE AUSTRALIAN MUSEUM. 



IV. 



MAMMALIA. 



Class I. — Mammalia. — Tliese are warm-blooded animals, 

 having a heart with four cavities, and a complete double circula- 

 tion ; possessed of two pairs of well developed limbs (except in 

 certain marine forms), which may be greatly modified to suit 

 individual rerjuirements ; having the lungs completely separated 

 from the abdomen ; the skin more or less clothed with hair ; and 

 in the female producing living young (except in Echidna and 

 Ornithorhynchus, see pages 49 and 50), which are nourished for 

 some time after birth, — hence the name Mammalia, from the Latin 

 Mamrna, a breast. Mammalia are divided into Orders as shown 

 on page 15. 



Order I. — BIMANA, or two-handed animals, is confined to 

 Human Beings, The history and structure of the different races 

 of men inhabiting the world are illustrated in the Museum by 

 skeletons, casts, and Ethnological specimens, which are referred 

 to more fully in chapters XIII. Osteology and XVI. Anthropology 

 and Ethnology. 



The human skeleton may be taken as a type of other mam- 

 malian skeletons, and of most other vertebrates. The four limbs 

 are present in all the Mammalia, whether we call them hands, 

 feet, wings, fins, or flippers ; the backbone is found in all, and so 

 is a skull to enclose the brain. 



The human race is generally recognised to be essentially one, 

 but it is divided in a most complex manner into varieties and 

 groups which cross and recross one another. 



Order II.— QUADRUMANA, or four-handed animals, 

 includes Monkeys and Lemurs. Their teeth are generally the 

 same as in man, but not always so regular. The thumbs on both 

 fore and liind limbs can be used as in man's hands — but some- 

 times the thumbs are wantinsf. 



Following modern scientific usage the name Quadrumana is not 

 correct, as the monkeys have really two hands and two feet, and in 



