n 



ventral surface, six strongly-chitinized sterna may be count- 

 ed. 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 sec- 

 ond 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 cau- 

 dal 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 pro- 

 ject somewhat 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 unequally divided by a transversal suture, producing 

 thus an additional small tergum. All of the terga are mem- 

 branous except the sixth and seventh, which are chitinized, 

 and are known respectively as the propygidium and pygidium. 

 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 pygidium and the sixth sternum there is a transversal 

 fissure, in which lie the anal and genital openings. 



