INTESTINE.

[Fig. 5] is a section of the same spider. The mouth is at a b, just under and behind the mandibles, and between the maxillæ. It has an upper, a, and under lip, b, each lined with a horny plate, in the middle of which runs a groove. When the lips are closed, the two grooves form a tube, which leads to the œsophagus, c, and so into the stomach. At the end of the œsophagus is the sucking-stomach. This consists of a flattened tube, to the top of which is attached a muscle, d, connected with the groove in the back; and to the bottom, muscles, f, attached to a tough diaphragm spreading across the thorax, and fastened between the legs on each side at g g. When these muscles contract, the top and bottom of the sucking-stomach are drawn apart, and whatever is in the œsophagus sucked in. By this pumping motion the spider is supposed to take liquid food from the mouth, and drive it backward into the abdomen. Just behind the sucking-stomach, the intestine gives off two branches, e e, which extend forward around the stomach muscle, and meet over the mouth. Each of these branches gives off on the outer side four smaller branches, m m m m, which extend downward,—one in front of each leg,—and unite on the under side of the thorax.

Fig. 5.

The intestine, o, continues backward through the abdomen to the anus, in the little knob behind the spinnerete. The brown mass which surrounds the intestine, and fills the abdomen above it, is supposed to be a secreting-organ discharging into the intestine at several points.