CHAP. XI - Functions and Instincts. Worms

Summary

We are now at length, after long wanderings, arrived, if I may so speak, at the limits of the Molluscan territory, and, having visited the capital, seem now to be upon the confines of the higher hemisphere of the animal kingdom, the inhabitants of which are distinguished by having their whole frame built upon a vertebral column, inclosing a medullary chord, and terminating, at its upper extremity, in a skull containing a developed brain.

But though we seem arrived at the confines of this higher order of animals, there are still many, and some superior to the most perfect of the Molluscans, in the entirety of their nervous system, and the habits and instincts which they manifest, to which we have not yet paid the attention that they merit. These animals are particularly distinguished from the preceding Classes, by the appearance, or actual existence of segments or joints in their bodies, especially in their legs, of what may be called an annular structure. They are divided into two great tribes, which, from this circumstance, have been called Annelidans, and Annulosans, and the last, with more propriety, Condylopes.

There is one tribe, however, amongst the Radiaries, as we have seen, that shews some slight traces of insection, I allude to the star-fish and sea-urchins, forming the main body of Lamarck's Order of Echinoderms.