Page:Popular Science Monthly Volume 33.djvu/599

Rh nervous system, which again is brought into relation with the external world by means of special sense-organs. It is a gelatinous bell, from the inner surface of which the pendent stomach hangs down like the bell-clapper, while the long, graceful, thread-like tentacles are attached at regular intervals around the opening of

 —Liriope scutigera, slightly magnified, drawn from Nature by W. K. Brooks. (The small figure in the left-hand lower corner is the planula of Turritopsis, greatly magnified; and the one in the right-hand corner, the root and the first bud of the Turritopsis hydroid.

the bell. The locomotor muscles are so distributed over the inner surface of the bell that their contraction squirts out the water in a jet which propels the animal in the opposite direction; they are then relaxed, and the elasticity of the gelatinous substance of the wall of the bell causes it to expand and to draw in another supply