OETHOPTERA OF NEW ENGLAND. 429 



tubes, Fig. 3, wr., and are supposed to correspond to the kidneys 

 of higher animals. The ileum is much smaller than the stomach, 

 and has numerous longitudinal ridges on its surface. The next 

 division of the digestive system is the colon., which is smaller than 

 the ileum, has a smooth surface, is somewhat twisted, and ends in 

 the much enlarged rectum, which ends in the anus, at the extremity 

 of the abdomen. The rectum has six large rectal glands on the 

 outside, the nature of which is unknown. The salivary glands are 

 shown in Fig. 3, sal.., extending from beneath the gastric coeca 

 forward to the mouth, where they empty their secretions. 



The ovaries, Fig. 3, ov., form a large mass before the eggs are 

 laid, and crowd the intestine somewhat out of place. The heart, 

 Figs. 3 and 4., consists of a long tube lying along the abdomen 

 just beneath the upper side, and has six enlarged places along its 

 course, probably where valves are situated within. The blood 

 flows through this tubular heart toward the head, and flows back 

 again among the viscera, bathing the surface of all the organs of 

 the body. 



All insects breathe by means of a complicated system of air 

 tubes distributed throughout the body, the air entering through 

 the spiracles or breathing holes which are arranged in a row along 

 each side of the body. From these spiracles air tubes pass in, a 

 short distance, connecting with tubes on each side which extend 

 through the abdomen into the thorax. Fig. 4, S. 



Branches extend from these tubes to a similar pair near the 

 back, Fig. 4, D, and another pair along the under side, Fig. 4, V. 

 The tubes send out numerous branches which divide and sub- 

 divide, the ultimate ends of which are closed. The blood, as it 

 flows from the head, bathes these tubes (called trachece) , and is 

 purified, as in the human lungs. In addition to the above system 

 of air tubes, those species which take long flights have a series of 

 air sacs connected with the air tubes. See Fig. 4, 1-7, and I, 

 II, III. 



The nervous system consists of a series of nerve centers 

 (ganglia), which are double, though quite fully fused together. 

 These are connected by two cords, which are united in some parts 

 of the body, but distinct in others. 



The first ganglion, Figs. 3, sp., and 5, is situated near the 

 central part of the head, and sends nerves to the ocelli, antennae 

 and eyes ; and the nervous cord which connects this ganglion with 

 the second separates, allowing the oesophagus to pass through the 

 opening. The second ganglion sends nerves to the mouth parts, 

 the third to the fore legs, the fourth to the middle legs and fore 



