Concerning this resemblance, Buffon has observed, when speaking of the ape, the most man-like (and so man-like) as to brain:[13] "Il ne pense pas: y a-t-il une preuve plus évidente que la matière seule, quoique parfaitement organisée, ne peut produire ni la pensée, ni la parole qui en est le signe, à moins qu'elle ne soit animée par un principe supérieur?"
As to the second sub-order, it contains some very curious forms. The typical lemurs (which inhabit Madagascar) have long fox-like snouts and long tails. Certain African forms (the genus Galago) are very active in their movements, and great leapers. A tailless group (the slender loris) is interesting, as presenting a diminutive quasi-human form, reflected, as it were, through a Lemurine prism, just as the rat-mole shows us a mole-form reflected through a rodent prism.
A little animal, the Tarsier, which is found on the islands of Celebes and Borneo, is very exceptional in its structure. Still more so is the aye-aye (Cheiromys). This very remarkable species was discovered by Sonnerat in Madagascar in 1770, and was never again seen till 1844, when a specimen was forwarded to Paris. It has now, however, become well known.
Inhabiting the sea are many beasts, which are, by mistake, popularly spoken of as "fishes." Such are the whales and the porpoises—animals which, in spite of their form and habit, suckle their young, and have hot blood, as all other mammals have. These creatures form an order by themselves, called Cetacea.
Another order of aquatic beasts is termed Sirenia, and the animals which compose it were long confounded with the Cetacea, from which, however, they are widely divergent in structure, in spite of the general similarity which exists between them in external appearance. The order Sirenia contains but two existing genera. One of these is the now well-known manatee (Manatus), the other is the dugong (Halicore)—an animal very similar to the manatee, and found in the rivers of regions about the Indian Ocean. A third form, the Rhytina, existed in the Aleutian Isles till recent times, but was extirpated almost as soon as discovered, from its incapacity for flight or defence, and from its flesh affording a welcome change of diet to hungry sailors.
The Cetacea and Sirenia are examples of creatures organized for a completely aquatic life—for never coming to land.
The forest-regions of South America offer to animal life so enormous a mass of foliage that it may not unjustly be termed a sea of verdure, and creatures there exist which are specially organized for a completely arboreal life—for never coming to the ground. Such creatures are the sloths, which pass their lives hanging back-downwards, suspended to the branches by their huge claws. Thus, they sleep without effort (from the peculiar mechanism of their limbs), and they move slowly from tree to tree, having no need to hurry after food, since they live suspended in the midst of a perennial banquet.
Nearly allied to the sloths were certain huge beasts, now extinct, which formerly inhabited the same Continent—such as the Megatherium and Mylodon, which rivalled or exceeded our largest rhinoceroses in bulk. They fed on the same food which nourishes the sloth, but obviously the branches of no tree could sustain such monsters. They obtained their leafy pasture, therefore, by a different method. Rearing themselves on their massive hind legs and powerful tail, as on a tripod, they embraced the trees with their vigorous arms, and swayed them to and fro, till the tree embraced was prostrated, and literally fell a prey to their efforts. These bulky creatures were protected against that danger which such a mode of life rendered imminent by a specially strong skull structure, which enabled them to bear a broken head with but little inconvenience.
In the same region of the earth are found the ant-eaters and armadillos, and more or less allied to them are the pangolins (Manis) of Africa and Asia. The horny scales which cover the bodies of the last-named animals caused them for some time to be associated with reptiles rather than with beasts, though they are true and perfect mammals. Lastly must be mentioned the aard-vark (Orycteropus) of South Africa.
All these creatures, from the sloths to the aard-vark, are commonly associated together in an order which is termed Edentata.