62 Annals Entomological Society of America [Vol. IX, 



Verhoeff, '03, termed the episternum the " coxopleure, " while 

 in the roach his "coxopleure" consists of the precoxale together 

 with the episternum. 



Audouin's, '24, term episternum is satisfactory and generally 

 accepted, while the other terms applied to the episternum are 

 useless synonyms. This confusion was brought about by the 

 misinterpretation of sclerites and by the tendency of writers 

 to set forth their own ideas of the terminology. In doing this, 

 they have invented new terms to suit their respective views 

 and have not given sufficient attention to the work and ter- 

 minology of previous investigators. 



Precoxale. The precoxale is situated in front of the 

 coxa and is either united or completely fused with the epister- 

 num. The end of this sclerite nearest the sternum may be free 

 as in Periplaneta (Fig. 3, pci), or it may be united or fused with 

 the sternum as in the mesothorax of Capnia (Fig. 4, PC2), 

 thereby forming a bridge connecting the episternum with the 

 sternum. Hence the term precoxal bridge or precoxale of 

 Crampton, '14. The portion nearest the sternum is sometimes 

 split transversely into one or two small sclerites, as in the 

 mesothorax of Forficula (Fig. 8, pco). In other cases the 

 precoxale is entirely fused with the episternum and sternum as 

 in the Coleoptera, Formicina, Diptera, etc. (Fig. 10, pc). A 

 portion of it may fuse with the episternum and a portion with 

 the sternum as illustrated in the metathorax of Forficitla 

 (Fig. 8, PC3), or it may disappear as in the prothorax of Macrox- 

 yela (Fig. 14). The division between sternum and episternum 

 in the metathorax of Forficnla (Fig. 8, eSs, VS3) is probably 

 secondary, although this condition is open to other inter- 

 pretations. 



The precoxale, while constant in position is extremely 

 variable in size and form. In Periplaneta, which is admittedly 

 a very primitive insect, the precoxale is similar in all three 

 thoracic segments, its dorsal portion being always fused with 

 the episternum, except in the prothorax, while the ventral 

 portion borders on the sternum, but is not strongly connected 

 with it (Fig. 3, pci, pC2, pCs). In the meso and metathorax, 

 there is a deep cleft in front of the pleural wing process, at the 

 mouth of which is a small sclerite, comparable to one of the 

 basalar sclerites, previously discussed (Fig. 3, pbao, pbas). 



