Page:Popular Science Monthly Volume 6.djvu/601

Rh and paddles the lobster owns (Fig. 15). He has six pairs attached to the head, eight pair to the breast (thorax), and six pairs to the body (abdomen); in all, twenty pairs, and very few of these appendages are alike.

You now have a pretty good idea of the exo-skeleton, or hard outside part of the lobster, and we shall look next at the soft parts inside (Fig. 22). The mouth seems a very good place to begin at, and you will find it between the mandibles, or jaws. In front of it is a lip, shaped like an escutcheon, and is called the labrum, which means lip. At the back of the mouth is another lip, the metastoma, meaning beyond the mouth, and this is looked upon as the lower lip. The mouth, as in the mussel, opens into a gullet, or œsophagus. This meat-pipe opens into a four-cornered box (Fig. 22)—the stomach—which is very curiously made.

Near the centre of the box the walls come almost together, dividing it into two parts: the front part is the larger, and it is called the cardiac end, because in the human body the first part of the stomach points toward the heart, but you see, in the lobster, it points away from the heart. It contains three strong, colored teeth, fastened to a T-shaped frame (Fig. 23), and worked by muscles which are fastened to the inside of the breastplate (carapace). These teeth meet in the middle of the stomach, and form a powerful grinding-machine, which crushes the food like the stones in a mill (Fig. 24). Sometimes, when you find the empty shell of a lobster on the sea-shore, you can see a perfect mould of the old mill—"the mill-wheel gone to decay." How the lobster sets out of his shell, and how he turns the mill out of his stomach, we shall study after a while. The small back part of the