436 



can be seen in the normal insect. If the body be softened and the 

 lateral margin of the terga extended, the pleura appear as membrane 

 between the margins of the terga and the sterna. In this membrane, 

 near the cephalic-lateral margin of the first eight segments, the ab- 

 dominal spiracles are found. The terga of all the segments are always 

 large, are bent around from the dorsum onto the lateral aspect of the 

 abdomen, and usually extend slightly onto the venter. A "single 

 tergum, then, has a dorsum and pleuron of its own. The terga are 

 usually transversely rugose on the dorsum, and the lateral margins are 

 always paler than the dorsum, and finely pilose. The apical margins of 

 all except the last segment have elevated subapical chitinous rings which 

 are frequently provided, especially in the terminal segments, with a 

 number of short, heavy setae. The apical margin of the tenth segment 

 may bear a long spine at the apex ( Fig. 1 10) , or the apical margin may 

 have a long, subapical, blunt process (Figs. 166, 167), or it may be 

 simply emarginate. The sterna are narrow transversely, with the 

 exception of the first two and the last two, and are more or less hidden 

 by the margins of the terga. The first sternum (Figs. 40, 42) is 

 usually subtrapezoidal with the cephalic margin concave. The second 

 sternum of the male is developed into an accessory copulatory appara- 

 tus which will be described later. In the female this sternum is sim- 

 ilar to sterna three to eight and consists of an oblong plate of chitin, 

 slightly wider cephalad, and having small ental projections at the ceph- 

 alo-lateral angles. The eighth sternum of the female is divided into 

 three sclerites (Figs. 109, 116), a single large proximal one and two 

 small, sometimes obsolete, ones which are intimately connected with 

 the first pair of gonapophyses. The ninth sternum (Figs. 109, 116) 

 is greatly reduced in the female, being represented by narrow sclerites 

 along the margins of the tergum extending from the proximal end to 

 about the distal third or half of the segment. The ninth sternum of 

 the male bears the genital opening, and on each side of this, and cov- 

 ering it, there is a more or less oval plate. These plates are known 

 as the parameres (pa, Figs. 118, 121, 147, 165, 171, 172, 183). The 

 tenth sternum is fused with the tergum on the lateral aspect. 



Abdominal Appendages. — This term includes the accessory gen- 

 italia and anal appendages of the male, and the ovipositor of the 

 female. 



Accessory Genitalia (Figs. 33, 97, 98, 101, 105, 107, 108, 120, 

 122). — The accessory genitalia of the male are derived from the sec- 

 ond and third sterna, and a portion sometimes from the second tergum. 

 The sperm duct opens in the ninth sternum and spermatozoa are trans- 

 ferred to the accessory pouch or vesicle by doubling the abdomen upon 



