In the next place come the Ruminantia, to take their site opposite the class of Birds, with whom they correspond in their susceptibility to domestication, large ears, fine sense of hearing, and timid disposition. The horns must be regarded as the obscure metatype (nachregung) of the feathers. These three families may be aptly termed Ungulata or Hoofed-animals.
Were matters to fare simply thus, then the center-building of this class would stand firm, and it would consequently not be difficult to say which animals stood below and which above it. For to the Apes are allied the Bears, to these the Dogs, Cats, and Martens, and to the latter again the Seals; all would rank above the Ungulata or Hoofed animals, and represent the proper or typical class of Thricozoa.
But the Thricozoa are Æsthetic or Sense-animals, and consequently the upper families must pass parallel to the organs of sense, if the lower correspond to the anatomical systems.
Now, if the eye has attained its maximum development in Man, the same must be said of the ear in the Apes, of the nose in the Bears, of the tongue in the Carnivora, and of the skin in the Seals.
Having so disposed of these, the only remaining Thricozoa are the Bats, Shrews, Moles, Marsupials, Sloths, and Rodentia.
In common parlance we compare the Bats with the Birds on account of their wings, unto which may be further added the large size of their ears. Their close relation, however, with the Shrews and Rodents assigns them a lower rank. They must be placed parallel with the Ptilota or Flies. The dental formula of the Bats resembles too so strikingly that of the Shrews that a rusty-grown prejudice can alone place the former in the neighbourhood of the Apes. They have obtained this post, without doubt, simply because they have but two mammæ, and these placed upon the chest.
The Moles cannot be removed from the Shrews.
The choice of position now remains between the Marsupials and Rodents. And to determine this point cannot prove difficult, for every one will place the former above the latter on account of their size, more perfect dental formula, and the hands, upon whose model the hind-feet have been in many species formed. To the Marsupials are annexed the Sloths, because several of them still possess marsupial or pouch-bones.
Viewed in this and in every other respect, the Rodentia stand or rank the lowest; and since the members of this family are much more numerous than those of any other, we may conclude that they fill up several families of the asarcose animals.
3562. The series would accordingly be as follows; first of all Rodents, then Sloths and Marsupials; with Moles, Shrews, and Bats, all as the repetition of the Dermatozoa. They are all Myoidal or Mouse-like in character. Next come the Whales, Pigs, and Ruminants as the repetitions of the Fishes, Reptiles, and Birds.