— ...6 — 



PARTS OF THE ABDOMEN. 



The abdomen is composed of a number of very much 

 flattened segments ; and its dorsal surface or tergum is com- 

 pletely covered by the elytra when the3^ are closed. On the 

 ventral surface, six strongly-chitinized sterna may be 

 counted. The first (basal) sternum is completely divided 

 by the coxal cavities, so that it appears as two triangular 

 pieces, lying laterad of the coxae. The cephalic margin of 

 the second sternum is emarginated on each side of the meson 

 by the coxal cavities, so that the mesal part of the cephalic 

 margin appears as an acute, cephalad-projecting process. 

 The third, fourth and fifth sterna are of about equal length 

 (caudo-cephalic), the sixth being longer and having its 

 caudal margin roundly pointed. The first, second and third 

 sterna are connate (firmly united, not movable on each other) , 

 although the sutural lines are distinct. All of the sterna 

 have strongly chitinized, lateral margins, which project some- 

 what dorsad, and then are narrowly inflexed over the dorso- 

 lateral margin of the abdomen. There are seven terga, the 

 tergal aspect corresponding to the sixth sternum being un- 

 equally divided by a transversal suture, producing thus an 

 additional small tergum. All of the terga are membranous 

 except the sixth and seventh, which are chitinized, and are 

 known respectively as the propygidium and pygidhim. The 

 propygidium is coarsely punctulated, but the surface of the 

 pygidium is smooth. Each tergum except the seventh bears 

 a pair of spiracles, located near the cephalo-lateral angles of 

 the terga. Between the lip-like caudal margin of the pygi- 

 dium and the sixth sternum there is a transversal fissure, in 

 which lie the anal and genital openings. 



