SUBFAMILY III. LOCUSTIN^D. 439 



Series XV. THE DIFFERENTIALS GROUP. 



Species of large size and robust form, having the general hue 

 brownish-yellow or reddish-brown, the postocular dark stripe 

 faint or wanting; disk of pronotum with sides subparallel, male, 

 feebly expanding, female, median cariua very low, usually per- 

 curreut, hind margin broadly obtuse-angulate ; teginina variable 

 as to species, fully developed or slightly abbreviated; prosternal 

 spine long, rather slender, subcylindrical ; interval between mesos- 

 ternal lobes of male twice or more as long as broad ; extremity of 

 male abdomen strongly swollen, usually distinctly upcurved; 

 supra-anal plate broad, shield-shaped or subtriaugular ; furcula 

 wanting ; cerci variable as to species ; subgenital plate longer than 

 broad, comparatively narrow, the apex but slightly elevated and 

 entire. 



Six closely related forms of this group are known from east 

 of the Mississippi, two of them of rather Avide distribution, the 

 other four recorded in small numbers only from Georgia and 

 Florida. 



Fig. 148. a, Extremity of male abdomen of Melanopliis clypcatits; c, same of M. jur- 

 catits; b, outline of male cercus of M. symmetricus. (After Scudder and Morse.) 



KEY TO EASTERN SPECIES OF DIFFERENTIALS GROUP. 



o. Cerci of male roughly boot-shaped, the apical foot as long as the basal 

 leg (PI. IV, p);hind tibiae yellow, rarely red in Pacific Coast speci- 

 mens. 205. DIFFEEKNTIALIS. 



aa. Cerci of male not boot-shaped; hind tibiae usually red. 



I). Apical margin of male cerci regularly obliquely convex or broadly 

 rounded. PONDEROSUS. 60 



bb. Apical margin of cerci not regularly convex or broadly rounded, 

 c. Cerci of male not forked. 



(I. Tegmina covering three-fourths of abdomen, subequal in 

 length to hind femora, their costal field dark testaceous, 

 discoidal field blackish, anal field light testaceous or wood- 

 brown ; apical margin of cerci broadly angulate, prolonged 

 above to form a triangular lobe (Fig. 148, a.) 



206. CLYPEATUS. 



dd. Tegmina reaching tip of abdomen, distinctly longer than hind 

 femora, their color brownish-yellow, but faintly marked 



60 This species is dimorphic in wing-length and has been treated under Division I, 

 p. 405, the short-winged form only being so far known from our territory. 



