The Probert Encyclopaedia of Nature

MAMMALIA

Mammalia is the mammal class of Craniates. The young are nourished by milk. The skin is covered in two types of glands: sweat glands and sebaceous glands. The sweat glands secrete a watery fluid to assist body cooling. The sebaceous glands secrete an oily fluid to maintain water resistance in the hair. The heart has two auricles and two ventricles.
Research Mammalia