70 Annals Entomological Society of America [Vol. IX, 



some Hymenoptera and Coleoptera they are all fused into one 

 sclerite. Three of these subdivisions are usually present in 

 most insects, while the other two occur in only a few. For these 

 sclerites, I shall use a modification of Crampton's '09, termi- 

 nology, designating the subdivisions of the sternum as ster- 

 nites. Thus as far as possible, without leading to confusion, 

 the subdivisions of the tergum, pleuron and sternum will be 

 designated by the endings tergite, pleurite, and sternite 

 respectively. 



The presternite (Fig. 4, prsi), or anterior division of the 

 sternum is derived from the verasternite ("sternum" or "basi- 

 sternum" of other writers) and is absent in most insects. In 

 the prothorax of Ectobia lapponica the presternite is in the 

 process .of becoming detached from the verasternite (Fig. 9, prs). 

 In the prothorax of Capnia it is completely detached from the 

 verasternite and lies directly in front of it (Fig. 4, prsi). It is 

 quite a large, oblong sclerite and has frequently been mistaken 

 for one of the neck sclerites, owing to its position. The pre- 

 sternite is also found in the meso- and metathorax of Capnia 

 (Fig. 4, prs2, prss) and in the prothorax of Forficida (Fig. 8, prs). 

 The presternite is also present in Raphidia and has been figured 

 in the metathorax of Pteronarcys by Comstock and Kochi, '02. 

 In the latter insect it is similar in shape to the presternite of the 

 prothorax of Ectobia lapponica and is attached to the veraster- 

 nite in the same manner. Comstock and Kochi, '02, have termed 

 it the "presternum." In all other insects examined, the 

 presternite is either absent or indistinguishably fused with the 

 verasternite. 



The verasternite is a large sclerite of variable shape lying 

 immediately posterior to the presternite, when the latter is 

 present (Fig. 8, vsi). It is found in all insects and is often fused 

 at its anterior corners with the precoxale, thereby forming the 

 connecting bridge between the episternum and sternum (Fig. 7, 

 vsi). In such insects as the Lepidoptera, Diptera, etc., the 

 verasternite is divided longitudinally by a median groove 

 formed by an infolding of the chitin (Fig. 14, vs). Internally 

 this groove is represented by a longitudinal, chitinous ridge. 

 In Ectobia the verasternite is divided diagonally by two sutures 

 into four sclerites and the precoxale is not fused with it (Fig. 

 9, vs). 



