Mammalia. Vertebrated animals having an internal, bony, cartilaginous skeleton, and a brain, with a double heart and warm blood, and suckling their young. This first Linnaean class is divided into seven orders, viz. : primates, bruta, fens, glires, peeora. belluae, and cete; including not only all the viviparous quadrupeds, but also the bat tribe, and seals and whales.