that the anatomy of mammals was similar in plan, if not in detail, to that of man, and we find Descartes, for example, in his "Discourse on Method" (Part V., 1637) advising those who wished to understand his theory of the action of the lungs and circulatory system, "to take the trouble of getting dissected in their presence the heart of some large animal possessed of lungs, for this is throughout sufficiently like the human" (ital. mihi). And it was further known that of all animals the monkeys are most nearly like man, both externally and internally. This was asserted by Aristotle and other classical authors but was fully demonstrated in a carefully prepared and illustrated work[1] on the anatomy and appearance of animals from the Jardin du Roi, by a committee of savants of the French Academy, appointed by the Grand Monarch.
That this work and these important facts came under the notice of Linnæus on the occasion of his visit to Paris in 1738 is not improbable. At any rate, Linnæus did not hesitate to follow the logical consequences of these facts, namely, that in a strictly zoological classification man would be grouped not only in the class mammalia, but even in the same ordinal division with the monkeys. Accordingly, in the tenth edition of the "Systema" the earlier name Anthropomorphæ is replaced hx Primates, and the genera Homo, Simia, Lemur, Vespertilio are grouped under that order. The Primates were thus regarded as the chiefs of the graded hierarchy of terrestrial beings, and consequently, as in nearly all subsequent schemes down to the Darwinian epoch, head the classified legions of creatures. This allocation of man to the order Primates was surely an instance of Linnæus's genius in surmising the true affinities of puzzling organisms, and led the way to the modern generalization that man is knit by ties of blood kinship to the Primates, and more remotely to the whole organic world.
The diagnostic definition given by Linnæus of the order Primates may be cited because it rests upon the princi]iles and theories which guided him in classification and which led to his most successful groupings, as well as to his serious blunders. This definition is as follows:
| Inferior front teeth iv. parallel, laniariform [canine] teeth solitary [i. e., in a single pair]. |
| Mammæ pectoral, one pair. |
| The anterior extremities are hands. |
| The arms are separated by clavicles, the gait usually on all fours ("incessu tetrapodo volgo"). |
| They climb trees and pluck the fruits thereof. |
That this definition was insufficient to exclude all extraneous genera from this really natural order is evident from the facts: (1) That under
- ↑ "Mémoires pour servir à l'Histoire naturelle des Animaux," à la Haye, 1715 (4to, 2 vols.), Redigées par Perrault et Dodart.
