JOUKNAX, OF ENTOMOLOGY AND ZOOLOGY 49 



witli the spiracle and with a large sac opposite and the arrange- 

 ment of the smaller sacs is as shown in Fig. 1, C. 



Along each side is a large tube-like trachea which is con- 

 nected with six spiracles as shown in Fig. 1, B, and also in 

 Fig. 2, B. 



In the ventral i)art of the abdominal region there are also 

 variations. In some there are live pairs of air sacs, not so wide 

 and more elongated than the smaller sacs of the dorsal region, 

 and uniformly arranged. These are connected with each other 

 and with the trachea whicli runs along the side, being attached 

 to the outside of the tube at the point where the Itrauches go to 

 the spiracles. Some of these air sacs are attached to the one 

 posterior by smaller tubes as shown in Fig. 2, A. The branches 

 at the caudal end of the long tracheal tube pass in to the 

 internal organs. 



Fig. 3 shows a variation from the uniform arrangement al- 

 though in this specimen there are also the five main air sacs on 

 each side but with different connections. It was difficult on 

 account of the stiff exo-skeleton to open the insect and lay back 

 the body wall without disturbing the natural arrangement of 

 the trachea^. At first I thought the air sacs as shown in Fig. 

 3 were drawn out of position but since examining other speci- 

 mens I have concluded that it is a variation. 



In this account there is no description given of numerous 

 small l)ranches from the large air sacs which go to various 

 parts of the abdominal region. 



(Contribution from the Zool-ogical Lahoratunj of Pomona College.) 



