320 DAVENPORT ACADEMY OF NATURAL SCIENCES. 



Extending from the end of the vertriculus directly baclcward to the 

 anus is the rectum. It is an enhirged sack-like organ, and is contracted 

 rather suddenly at the small anus. 



Of the circulatory system I have made no positive observations that 

 are of any value. The blood (or protoplasm) after leaving the stomach, 

 appears to circulate all through the cavity of the body not otherwise oc- 

 cupied. If there is a dorsal vessel I have seen no traces of it, neither 

 have I seen any indications of a rhythmic motion. 



The respiratory organs consist of the spiracles and trachea. The spir- 

 acles are four in number, situated on the under side of the thorax as 

 above described. Each spiracle consists of an elongated opening in a 

 kidney-shaped chitinous piece. Extending inward from each spiracle is a 

 large tracheal tube, which soon divides into three main branches, and 

 these again each divide into two secondary branches. Of the six sec- 

 ondary trachea thus formed about each of the anterior spiracles, one ex- 

 tends near the ventral surface toward the opposite side until it meets 

 and unites with a similar trachea from the opposite spiracle ; a second 

 extends dorsally and connects with its fellow in the same manner ; a 

 third extends longitudinally near the ventral surface until it meets with 

 a similar trachea from the posterior spiracle on the same side ; a fourth 

 extends inward and backward near the dorsal surface until it meets 

 with a similar trachea from the posterior spiracle on the same side ; the 

 fifth and sixth extend forward, sending out several branches which lie 

 free in the head. Of the six secondary tracheae formed about each of 

 the Yjosterior spiracles, two connect with the tracheae from the anterior 

 spiracle on the same side ; a third extends near the ventral surface to- 

 ward the opposite side until it connects with its fellow from the oppo- 

 site spiracle; a fourth extends near the dorsal surface, inward and then 

 backward into the fourth abdominal segment where it unites with its fellow 

 from the opposite spiracle ; the fifth and sixth extend backward sending 

 forth several branches which lie free in the abdomen. The junction point 

 of the connecting tracheae is usually marked with a slight irregularity, 

 which seems to indicate that at some period in the life of the insect they 

 were not so connected but have grown together. By this connection of the 

 tracheae, respiration of the insect would not be interfered with even 

 though one or more of the spiracles should become stopped up. This 

 description of the tracheae applies more properly to tlie younger states of 

 the larva. In the adult female it is fundamentally the same, but the 

 branches of the tracheae become exceedingly numerous, permeating 

 every part of the body, and even the tracheie connecting the spiracles 

 appear to send forth branches, which is certainly not the case in the 

 young. 



Adipose tissue. Whenever the insect is about to undergo a moult or 

 other fast, and to a less extent at other times, it lays up in the otherwise 

 unoccupied parts of the body cavity a greater or less quantity of 

 spherical food globules,— exactly similar in appearance to the yolk 

 globules remaining in the young at birth. 



