Members or Limbs.
3393. In these animals the formation of limbs or members must be wholly attained. Everything, that works, must work to the production of limbs. The whole body becomes limb.
3394. With the perfected nervous and respiratory system the bones and muscles make also a perfect appearance. The skeleton is hard, complete, and full of air instead of marrow; the muscles are red and separated, the movements free and complex.
3395. The elevated condition of the motor system is demonstrated in the limbs, which here appear in the greatest diversity. There are only two pairs of limbs, thoracic, and abdominal or sexual members. These two are equivalent, so long only as the sexual and abdominal cavity belonging to the trunk proper predominate, and therefore preserve the equilibrium. But the limbs, which have been given to serve the office of the trunk, are destined for progression or swimming, and are simply terrestrial or aquatic members.
3396. The higher limbs are thoracic respiratory members, which are filled with air and clothed with tracheæ, thus exercising a function conformable to the thorax. The thorax has an aerial character. The highest thoracic limbs must be aerial members.
3397. As the abdominal members move upon the earth or in the water, so do the thoracic in the air. The terrestrial limbs are feet, the aerial limbs, wings.
3398. The wings are in the member-formation the extremes of the thoracic limbs. It does not follow from this that they are the noblest in rank, but only that they are the uttermost unto which bodily motion can attain.
3399. The winged animal is the Bird.
3400. The Bird is an Insect with fleshy limbs.
3401. The wings of Birds repeat the alary appendages of Insects in the flesh.