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ENTOMOLOGICAL NEWS. 



[March, '09 



prescutnm; 2 and 3, the separated and divided halves of the 

 scutum; 4, scittellum; and PN, postscutellum. The postscutel- 

 lum (pseudonotum) is not present in any Orthoptera. The 

 apparent four divisions of the Acridiid pronotum are second- 

 ary and due to internal ridges, the principle of which assists 

 the notum to perform its double role of notum and pleurum. 



The following is a brief statement of the fundamental struc- 

 ture of the tergum of any wing-bearing segment (cf. text, 

 fig. i): 



anr 



ANP 



PJVP 



AxC 



pnr 



Observe first the two tergal plates, the notum (N) and the 

 pseudonotum or postnotum (PN}. The former is the only ter- 

 gal plate of nymphal forms and of all stages in Orthoptera. 

 It carries the wings by its anterior and posterior wing processes 

 (ANP and PNP}, while its posterior angles are produced into 

 the axillary cords (A.vC) which form the posterior margins of 

 the basal membranes of the wings. On the ventral side the 

 notum presents an anterior and a posterior marginal ridge gen- 

 erally folded down upon the ventral surface, the second often 

 leaving a wide, free reduplication back of it. Between these 

 but nearer the second is a V-shaped ridge, the entodorsum of 

 Amans (1885), with its apex forward. These three ventral 

 ridges commonly show on the dorsal surface as three lines (anr, 

 v and pnr). This structure is fundamental, and common to 



