1916] Thoracic and Cervical Sclerites of Insects 55 



pleuron, but is the epimeron of the mesothorax. It extends 

 posteriorly as a sort of flap covering the metathoracic epimeron, 

 which would easily escape notice unless closely observed. 

 Heymons was confused in the use of his own term subcoxa, 

 which has led to its misinterpretation by other workers. Ender- 

 lein and also Berlese thought the "subcoxa" corresponded to 

 the trochantin. Borner considered it equivalent to his "mero- 

 sternum" or pleuron. Verhoeff regarded it as representing the 

 coxopleure (episternum) and trochantin. 



Epimeron. The epimeron varies greatly in size and shape 

 in different insects. Most writers consider it as a single sclerite, 

 which is usually the case (Fig. 8, emi). 



In the prothorax of Periplaneta there is a small sclerite, 

 which has become spHt off from the posterior edge of the 

 epimeron, and may be termed the postepimeron (Fig. 3, pemi). 

 Snodgrass, '08, applied this term to the subalar plate. It has 

 since been discarded and so far as I know, has never been 

 applied to any other sclerite. Therefore, as it describes the 

 exact position of the sclerite, which has become detached from 

 the posterior edge of the epimeron, I have adopted it to designate 

 the sclerite in question. In the prothorax of Capnia (Fig. 4, 

 pemi), there is a large sclerite comparable to the postepimeron, 

 which is likewise split off from the posterior edge of the epimeron 

 and extends behind the coxa until it meets the furcasternite, 

 thereby forming the postcoxal bridge or postcoxale (Crampton, 

 '14). In the mesothorax of Corydalis (Fig. 10, pema) the 

 epimeron is a single sclerite, a projection of which extends 

 behind the coxa. In many Coleoptera and Tenthredinidas 

 (prothorax of Dolerus (Fig. 12, emi) the epimeron is greatly 

 reduced in size. 



The epimeron is often divided into two sclerites by a trans- 

 verse suture. This condition can be seen in the mesothorax of 

 such insects as Mantispa, Chrysopa, Leptis, and in some 

 Tipulidas and Tabanidas (Figs. 1 and 2, emg). In Diptera the 

 lower portion of the epimeron of the mesothorax is usually fused 

 with the meron, being separated by a suture, although the 

 suture is often wanting (Figs. 1 and 11, mp). Packard, '80, 

 seems to have been the first to apply terms to the subdivisions 

 of the epimeron. In describing the thorax of Mantispa, he 

 termed the upper region, the sur-epimeron and the lower the 



