Page:Natural History, Mollusca.djvu/151

Rh interior callous lining is beset with firm, horny processes, in the form of rhomboidal plates or molar teeth, which serve to compress the softened vegetable matter transmitted in small portions from the first stomach. The third cavity of this complex apparatus is placed on the left side of the body; its interior surface is studded with sharp, horny spines, resembling canine teeth, to pierce and subdivide the coarse food, and thus prepare it for the action of the gastric juice, and other fluids accessory to digestion, which enter the stomach from adjacent organs.

SECOND AND THIRD STOMACHS OF SEA-HARE LAID OPEN.

The complexity of this structure has reference to the coarseness of the materials on which the animal subsists—the leathery fronds of the olive sea- weeds, which slowly and with difficulty yield their nutritive elements to the digestive functions.

The circulation of the blood in these animals has been considered, on the high authority of Cuvier, to present extraordinary peculiarities. The