Vol. XXV] ENTOMOLOGICAL NEWS IQ 



(Fig. 2), and a lateral portion (one on either side), the pleu- 

 rophragmite, Plph (Fig. 2). These are best seen in the Dip- 

 tera and Odonata. The postscutellar plates Psl (Fig. 6) of 

 the cockroach, doubtless are the representatives of the post- 

 scutellum in other insects. 



The various subdivisions of the tergal plates described 

 above, are not met with in all insects, those usually present be- 

 ing the prescutum (Psc), the scutum (Sc), the scutellum 

 (SI), and the postscutellum (Psl). 



The small tergal plates, or intertergites, It (Fig. 4) occur- 

 ring in front of the anterior tergal plate in such insects as 

 Corydalis, are doubtless homologous 'with the dorsal cervical 

 sclerites It (Fig. 3) occurring in front of the pronotum of the 

 cockroach and other insects. These will be discussed under 

 the consideration of the intersegmental sclerites. 



PLEURITES Situated immediately below the wing is a sub- 

 alar plate, the subalare, Asa (Figs. 2, 4, 5 and 6). There are 

 sometimes two of these, an anterior and posterior subalare, 

 Asa and Psa (Fig. 5), but only the anterior one is large enough 

 to be of any importance. The principal plate of the pleural 

 region is the eupleurite, composed of the regions Em, Es and 

 Lpl (Figs, i and 2). This was in all probability a single 

 plate originally, but later became divided into a number of 

 sub-regions by the formation of sutures. A more or less 

 oblique infolding of the integument whose external manifesta- 

 tion in the pleural suture g (of all figures) extends from the 

 top of this plate to the bottom of it. Internally, an "implex" 

 or ridge called the pleural ridge, or apodeme, likewise extends 

 from top to bottom on the inner surface of the plate. The re- 

 gion immediately posterior to the pleural suture g, is the epi- 

 m-eron, Em (in all figures). The epimeron may be subdivided 

 into an upper and a lower region Ppl and Hem (Figs. 2 and 4) 

 in such insects as Mantis pa, Chrysopa, etc., but this is of some- 

 what rare occurrence. 



The region immediately anterior to the pleural suture g is 

 the episternwm, Es (in all figures). In the mesothorax of the 

 earwig, the formation of a second suture e (Fig. i) marks off 

 the later oplenrite, Lpl, from the remainder of the pleural plate. 



