We will now turn for a short space to the lower divisions of the animal kingdom.

The Echinodermata (star-fishes, sea-urchins, etc.

) are furnished with remarkable organs, called pedicellariae, which consist, when well developed, of a tridactyle forceps--that is, of one formed of three serrated arms, neatly fitting together and placed on the summit of a flexible stem, moved by muscles.