76 Annals Entomological Society of America [Vol. IX, 



Snodgrass, '10, from a study of the Hymenopteron thorax, 

 concluded that the large sclerite which lies in front of the coxa 

 and ''prosternum" (prothoracic verasternite) of sawflies, was 

 the " proepisternum " (Fig. 15, Ics). He bases his claim upon 

 the position of the pleural suture. A small sclerite which 

 adjoins the "proepisternum" dorsally in Dolerus, he admits is 

 a cervical sclerite (Fig. 12, Ics). The conclusions reached by 

 Snodgrass, '10, appear incorrect for several reasons. It is more 

 probable that the conditions found in the prothorax of sawflies, 

 is the result of a fusion of the cervical sclerites with the epister- 

 num, in which the cervicals have become enlarged and the 

 episternum and epimeron have become greatly reduced in size. 

 The fusion and enlargement of the cervicals is very noticeable 

 in the higher insects (Tipulidae) while a reduction of the epister- 

 num and epimeron is found in practically all insects. Further- 

 more, the episternum never meets in front of the prothoracic 

 verasternite and never articulates with the head, as do the 

 cervical sclerites and also the "proepisternum" of Snodgrass, 

 '10, in the sawflies. 



A more conclusive proof that sawflies have a large lateral 

 cervical may be obtained from a study of Abia, Dolerus, and 

 Macroxyela in the order named. In the prothorax of Abia the 

 precoxale or bridge which connects the episternum with the 

 verasternite in a large number of insects can be plainly seen 

 (Fig. 15, pc). It extends from the coxal process to the veraster- 

 nite, thereby connecting the episternum and verasternite. The 

 episternum has never been known to occur in front of the 

 precoxale, but the cervical sclerites are always situated anterior 

 to it. The large sclerite which lies in front of the coxa and the 

 "proepisternum," also lies in front of the precoxale. Hence 

 this sclerite cannot be the prothoracic episternum, or "pro- 

 episternum," but must be a lateral cervical sclerite. In Dolerus 

 the precoxale is in the process of disappearing (Fig. 12, pc). It 

 is represented on either side of the prothoracic verasternite by a 

 small sclerite (Fig. 12, pc), while in Macroxyela it has entirely 

 disappeared (Fig. 14), In the latter insect however, the vera- 

 sternite has greatly increased in size and may possibly represent 

 the fusion product of the verasternite and part of the precoxale 

 (Fig. 14, vs). A cleft indicating a possible splitting of the 

 lateral cervical is seen in Macroxyela (Fig. 14). The episternum 

 and epimeron are clearly marked off by sutures in the prothorax 



