50 PROC. ENT. SOC. WASH., VOL. 20, NO. 3, MAR., 1918 



does not apply to the term presternum, which, unlike the terms 

 sternellum and poststernellum, had practically always been used 

 to designate the plate ps (of fig. 14) alone (Meinert, 1867, Corn- 

 stock and Kochi, 1902, Crampton, 1908, etc.), and its application 

 was therefore fixed by general usage before Hopkins attempted 

 to apply it to the sclerites of the Coleoptera. 



If the previous usages of the terms sternellum, poststernellum, 

 etc., were disregarded, the equivalence of the terms here employed, 

 as expressed in the terminology of McLeay, 1830, might be 

 tabulated as follows. 







Presternum . . Praesternum 



Basisternum "Sternum" (Basisternum or Eusternum) 



Furcasternum Sternellum 



Spinasternum Poststernum or Poststernellum 



Pleural Subdivisions. 



The entire lateral region of a segment, including both the 

 sclerites and t-he more membranous region as well, is called the 

 pleuron i.e., the region between the alar area, al and the coxa 

 ex, in figures 18, 19, 21, etc. In the pleural region of many 

 insects, there occurs a distinct plate called the pleural plate or 

 eupleuron, ep of figures 18. 19, etc. As first pointed out by the 

 writer (Crampton, 1908, page 14) the pleural plate becomes 

 divided into an episternal region, es, and an epimeral region, em, 

 by an inpocketing, or infolding of the integument, possibly due 

 to the stress of the muscles attached to this region. The internal 

 fold forms the apodeme for muscle attachment, while the external 

 lips of the pocket meet to form the pleural suture, or dividing 

 line between the episternum, es, and the epimeron, em. 



Beiiese, 1909, considers that the epimeron, em of figures 18, 

 19, etc., is a detached portion of the tergal region, while the epi- 

 sternum, es, is a portion of the sternal region. It is not clear, 

 however, how he arrived at the conclusion that the episternum 

 and epimeron are not portions of a single plate, for this can be 

 readily seen in both adult and larval insects, and none of the ob- 

 served facts is in harmony with his view. 



Boerner, 1903, at first thought that the episternum and epi- 

 meron are detached portions of the sternal region, and Craig- 

 head, 1916, came to a similar conclusion from a study of the mus- 

 culature of larval Coleoptera. Boerner, however, later discarded 

 this view in favor of Heymons' idea of the pleural plate represent- 

 ing a basal portion of the leg. 



Miall and Denny, 1886 (page 61), suggested that the p!ur:i] 

 plate represents the basal segment of the log which has "become 



