272 A HISTORY OF 



from their internal structure. Some have the heart with two ven 

 tricles, and hot red blood ; namely, quadrupeds and birds. The 

 quadrupeds are viviparousj and the birds oviparous. 



Some havo the heart with one ventricle, and cold red blood ; 

 namely, amphibia and fishes. The amphibia are furnished with lungs ; 

 the fishes, with gills. 



Some have the heart with one ventricle, and cold white serum ; 

 namely, insects and worms : the insects have feelers ; and the worms, 

 holders. 



The distinctions of quadrupeds, or animals with paps, as he calls 

 them, are taken from their teeth. He divides them into seven orders ; 

 to which he gives names that are not easy of translation : Primates 

 or principles, with four cutting teeth in each jaw ; Bruta, or brutes, 

 with no cutting teeth ; Ferae, or wild beasts, with generally six cut- 

 ting teeth in each jaw ; Glires, or dormice, with two cutting teeth, 

 both above and below; Pecora, or cattle, with many cutting teeth 

 above, and none below ; Belluse, or beasts, with the fore-teeth blunt ; 

 Cetae, or those of the whale kind, with cartilaginous teeth. I have 

 but just sketched out this system, as being, in its own nature, the 

 closest abridgment ; it would lake volumes to dilate it to its proper 

 length. The names of the different animals, and their classes, alone 

 make two thick octavo volumes ; and yet nothing is given but the 

 slightest description of each. I have omitted all criticism also upon 

 the accuracy of the preceding systems : this has been done both by 

 Buffon and Daubenton, not with less truth than humour ; for they 

 had tr^ much good sense not to see the absurdity of multiplying the 

 terms of science to no end, and disappointing our curiosity rather 

 with a catalogue of nature's varieties, than a history of nature. 



Instead, therefore, of taxing the memory and teazing the patience 

 with such a variety of divisions and subdivisions, I will take leave 

 to class the productions of nature in the most obvious, though not in 

 the most accurate manner. In natural history, of all other sciences; 

 there is the least danger of obscurity. In morals, or in metaphysics, 

 every definition must be precise, because those sciences are built upon 

 definitions ; but it is otherwise in those subjects where the exhibition 

 of the object itself is always capable of correcting the error. Thus, 

 it may often happen that in a lax system of natural history, a creature 

 may be ranked among quadrupeds that belongs more properly to the 

 fish or the insect classes. But that can produce very little confusion, 

 and every reader can thus make a system the most agreeable to his 

 own imagination. It will be of no manner of consequence whether 

 we call a bird or an insect a quadruped, if we are careful in marking 

 all its distinctions: the uncertainty in reasoning, or thinking, that those 

 approximations of the different kinds of animals produce, is but very 

 small, and happens but very rarely ; whereas the labour that natural- 

 ists have been at to keep the kinds asunder, has been excessive 

 This, in general, has given birth to that variety of systems which we 

 have just mentioned, each of which seems to be almost as good as the 

 preceding. 



Taking, therefore, this latitude, and using method only where ii 

 crutributes to conciseness or r^rsnicuity, we shall divide animated 



