CLASSIFICATION OF ANIMALS. 25 



and the structure of the whole animal, which was performed by 

 the anatomist. As the [subject of the] first has an immediate con- 

 nexion with [that of] the second, the describers of form conjectured 

 what the structure ought to be by consulting the works of the anatomist; 

 and the anatomist conjectured what the living history is or ought to be 

 from the Natural History of the others ; filling up what he conceived 

 to be just, and fancy supplying the rest. But such union of knowledge 

 does not properly match. It is one building built at different times, — 

 an addition to an original plan. It is no wonder, therefore, that the 

 whole is imperfect. 



This [partial or restricted study] confined them very much in their 

 mode of classing or arranging. Thus, for instance, Linnaeus, catching 

 the idea that all the animals which were formerly called ' Quadrupeds ' 

 had mammae, therefore called them by that name [mammalia], which 

 included the whole 1 . But, from the want of further knowledge, he has 

 divided these again according to the situation of those parts ; bringing, for 

 example, the human kind, the elephant, the bat, &c, into one order ; 

 whereas he should only have reduced the situation of the parts themselves 

 into different classes ; [thus classifying nipples] according to situation ; 

 but not [to have] classed the animals according to those situations 2 . 



Of the Classes of Animals. 



"We divide Animals into Classes, Tribes, Genera, and Species. The 

 three first are perhaps arbitrary ; but the last is absolute [or natural]. 

 Varieties depend neither on species nor choice, but are a kind of 

 accident. 



Classes of Animals according to their Hearts. 



1. Tetracoilia, those that have four cavities [in the heart]. 



2. Tricoilia, those that have three cavities, which includes both land, 

 sea, and amphibious animals 3 . 



3. Dicoilia, those that have only two cavities, as Gill-fish. 



4. MonocoiUa, those that have but one cavity, such as all kinds of 

 Insects. 



1 [i. e. not only the hairy warm-blooded quadrupeds, but the whale-kind and 

 mankind.] 



2 [The subsequent classifications of the Mammalia by Cuvier and others show the 

 perspicuity with which Hunter detected the artificial nature of the principal character 

 employed by Linnaeus in some of the earlier editions of the ' Systema Naturae.'] 



3 [As, for example, the Land Tortoise, the Turtle, the Frog. &c.] 



