REHN AND HEBARD 15 



look very different but a careful examination, particularly of the 

 genitalia, will show them to be identical. "We have given data 

 on these features under the specific treatments. The width of 

 the fastigium is occasionally variable within specific limits, as in 

 the case of the very plastic concinnum. This, however, is quite 

 exceptional, as the fastigial width is generally a constant character. 

 In the stridulating field of the male tegmina we find some varia- 

 tion in the exact form of the speculum, the bounding veins vary- 

 ing somewhat in their exact curve or in their degree of divergence 

 from the body axis when straight, but these differences are of 

 secondary importance and the relative proportions of the specu- 

 lum and direction of the stridulating vein remain the same. 

 The peculiarly elongate form of the speculum in volantwn and 

 hradleyi is Cjuite distinctive and in no way approached in the other 

 species of the genus. The exact curve and relative length of the 

 ovipositor show little individual variation except in the very plas- 

 tic conci7i7ium, where we have certain female individuals in 

 certain localities and all the female individuals in other localities 

 developing a much longer and relatively straighter ovipositor 

 than usual. Between the two extremes of ovipositor form in this 

 remarkable species we find numerous intermediates and Ave have 

 gone into this question of ovipositor form quite fully under the 

 specific treatment. 



Synonymic Notes. — Two species have been referred to, or 

 described under, this genus which have caused much difference 

 of opinion. These are Locusta agilis DeGeer from Pennsylvania^ 

 and Orchelimum gracile Harris from Massachusetts.^ The 

 identity of the first as a species of the genus Orchelimum is uni- 

 versally admitted, but it has been variously considered the same 

 as Harris' vulgare, Redtenbacher's laticcmda and Scudder's con- 

 cinnum. Several times DeGeer's species was correctlj^ identified 

 but it was never associated with the Redtenbacherian species, 

 two of which (spinulosum and nitidum) are sj^nonj'ms of it. 

 Harris' gracile we are certain was correctly referred by Scudder 

 when he synonj^mized it under Conocephalus fasciatus (DeGeer). 

 The description fits that species, but unfortunately the figure 



* M6m. Hist. Ins., iii, p. 4.57, pi. 40, fi^. 3,(1773). 

 s Treat. Ins. New Eng. Inj. Veget., p. 131,(1841). 



TRANS. AM. ENT. SOC, XLI. 



