3130. Through the increased process of oxydation the tegument hardens and is converted into horn. All induration, however, only takes place in opposition to soft places. The tegument therefore separates into hard and soft rings—Annulate animals.
3131. The annulate tegument is a tracheal tube wholly converted into a body. To distinguish it from the general tegument it may be called the cutis or skin—Cutaneous animals. The annular tegument may be regarded as a series of cysts placed one behind the other. The Annulate animals are therefore multiplied Malacozoa; Mucus-animals of the third power—Ovum3.
The respiratory organs, being in their lowest condition, will not as yet be freed from the tegument; the vessels simply form a network or projecting filaments and lamellæ—reticular branchiæ; as in the Worms. The tentacular organs, from being yet soft and thus scarcely moveable, are still very imperfect. Upon the lowest stage the tegument or skin simply feels; in the next place papillæ, and finally filaments, originate, especially about the mouth—Cutaneous, Papillary and Filamentary animals.
3132. If the tegument, as being the original branchial membrane, is converted into horn; then the branchiæ cannot continue as retia, but must elongate above the tegument into filaments, ramules or lamellæ.
With this, these elongated branchiæ separate into two organs, one part of them becoming indurated in like manner with the general tegument, and supporting the other as gill. Horny branchial filaments, which contain vessels, nerves, and fibres, are called feet—Pedal animals.
3133. The limbs or members of these animals are simply hollow tegument, hollow hair, and are therefore thoroughly different from the bones or the animal system.
The tegument thus hardens around the soft parts and the viscera. A horny coat of mail originates, and thus we have horny or mailed animals, in opposition to the Malaco-or Conchozoa.
3134. Beneath the horn, however, there must still be soft skin, and this becomes fibrous by the strong oxydation which it undergoes. Fibrous fascicles are attached to the coat of mail and to the hollow limbs, and are consequently within the tubes.
3135. These fibrous bundles are not flesh, but a fibre-drawn tegument, so that there are also no true muscles. They must on that account too be numberless.
3136. The articulations or joints are external not internal; they thus consist of tegumental tubes, not of bones, abutting against each other, and are not surrounded by flesh. Hence, like all the preceding groups they also are devoid of flesh—asarcose animals like all the preceding ones.