310 Annals Entomological Society of America [Vol. XII, 



SUMMARY OF CHARACTERISTICS OF THE ORDERS. 



Based, on the Terminal Abdominal Structures of the 

 Females of Types Examined. 



Orthoptera — Eighth sternum more or less modified as a 

 subgenital plate, but leaving ovipositor exposed; ninth sternum 

 vertical or nearly so; valvifers (sometimes absent) in contact 

 with ninth tergum and its marginal apodeme; ovipositor 

 well developed (rarely vestigial or absent), with three pairs of 

 valvulas; basivalvulse rarely well developed; a superior inter- 

 valvula connecting bases of dorsal valvulae, which cover inner 

 valvulse and have two pairs of apophyses (superior sometimes 

 indistinct or absent) ; inner valvulse, when not vestigial, with 

 rami, intervalvular membrane and pons, the rami with longi- 

 tudinal ridge which fits into groove on ventral valvulas; an 

 inferior intervalvula connected separately with rami and inferior 

 apophyses; tenth sternal region not defined, unchitinized ; 

 cerci un segmented (two-segmented in Tridactylus) ; supra- 

 anal plate well developed, sometimes fused with but not con- 

 cealed by tenth tergite; paraprocts usually well developed. 



Nymph: Valvulse all slender, dorsal and ventral pairs 

 developing from ventral surface of ninth sternum; styli rarely 

 distinct and usually disappearing at a very early stage. 



Grylloblattoidea — Eighth sternum unmodified in form, ovi- 

 positor exposed; ninth sternum, valvifers and ninth tergal 

 apodeme as in the Orthoptera; ovipositor well developed, with 

 three pairs of valvulae; basivalvulas exposed, heavily chitinized, 

 superior intervalvula absent ; dorsal valvulce covering inner pair ; 

 both pairs of apophyses present, inferior apophyses joining 

 one another medially, there being no separate inferior inter- 

 valvula; inner valvulas well developed, with rami, intervalvular 

 membrane and pons; rami fused with inferior apophyses and 

 connected with ventral valves as in Orthoptera; tenth segment 

 annular; cerci, slender eight-segmented; supra-anal plate small, 

 but not concealed by tenth tergite; paraprocts not large, 

 unchitinized. 



Phasmoidea — -Eighth sternum modified, usually forming a 

 very large flap-like subgenital plate, largely concealing the 

 ovipositor; ninth sternal regional horizontal; valvifers and 



