22 MAMMALIA. 



by an arrangement altogether different from the others. Every 

 peculiarity of organization proper to each of these classes, and 

 especially such as belong to motion and external sensation, 

 have a close and necessary relation with the characters now enu- 

 merated. 



CLASS L MAMMALIA. 



Vertebrated animals with red and warm blood, breathing 

 through lungs, viviparous, and suckling their young with 

 milk formed in their breasts or mammce. 



THE earliest writers on the Mammalia are Aristotle and Pliny, 

 afterwards -^Elian and Oppian. ./Elian has a work on the nature 

 of animals, and Oppian a Treatise on Hunting, in which lie 

 treats of wild animals. Many other writers, however, incidentally 

 notice the animals known to them, either on account of their use 

 to man, or their ferocity, such as Hippocrates, Cato, Columella, 

 Caesar, Seneca, Varro, and Athenaeus. 



It was not till after the revival of letters in Europe that the 

 study of Natural History began to assume a regular form. 

 Conrad Gesner in 1551 published a history of quadrupeds, in 

 which, though he treated of these animals in the alphabetical 

 order of their names, he grouped together some natural genera, 

 as apes, horses, deer, oxen, &c. He besides made a division of 

 oviparous quadrupeds for the tortoises, lizards, and frogs. Aldro- 

 vandus, Johnston, and others followed the steps of Gesner in the 

 following century, without much advancing the progress of the 

 science. 



In 1693 our celebrated countryman John Ray published his 

 Synopsis Methodica Animalmm Quadrupedum, the first regu- 

 lar system of mammiferous animals, and the basis of all which 

 have since appeared, in which he divided the Mammalia into 

 two great classes, viz. those which have hoofs and those which 

 have nails. 



The first class is subdivided into >Solipedes,such as the horse; 

 those which have cloven feet, as the sheep, and animals which 



