1922] Kershaw and Muir: Genitalia of Homoptera 203 



Orthoptera, may represent the only chitinized portion of the 

 ninth sternite ; they form the supports of the posterior processes. 



The median processes (Figs. 2 and 4, g2) lie immediately 

 posterior to the anterior processes and are represented by a 

 single, median process bifurcate on apical third and grooved 

 along the ventral surface. This process is joined to the anterior 

 processes by a ' tongue and groove joint and together they 

 operate as the ovipositor, the gonopore opening at the base of g2 

 and the eggs passing along the ventral groove between gl 

 into the puncture made by the ovipositor. The posterior 

 processes (Figs. 2 and 4, g3) are large and hold a lateral position 

 slightly posterior to g2, and form a sheath for gl and g2 when 

 at rest. Beyond the pygofer is the anal segment (Fig. 2, 10 

 and 11) which is composed of the tenth and eleventh segment. 

 Beneath the anus is the anal style (Fig. 2, a. s.), a median 

 organ grooved along its dorsal surface. In no Homopteron, in 

 either the young or adult, are the cerci present so far as we have 

 observed.* Whether an anal style is present in Psocida? 

 where cerci are absent we are unable to say. 



If we dissect an immature imago from the nymph al skin 

 just before it moults we find that the apices of the adult, gl, g2 

 and gS rest within the nymphal gl, g2 and g3 so there can be 

 no question as to their homology. 



Walkert in his admirable study of the ovipositor of 

 Orthoptera, has shown good reasons for considering g3 as the 

 coxites of the ninth sternite. In the nymphal stages of some 

 Orthoptera g3 carry the styles which are lost before the adult 

 stage is reached. In many Odonata these styles are retained 

 in the adult. In the Cercopidae there is evidence to indicate 

 that gl are the coxites of the eighth sternite but none to indicate 

 that g3 are the coxites of the ninth. If they be, then the area 

 between them and the tenth sternite is not the ninth sternite. 

 This leaves g2 as the only true gonapophyses and their origin 

 is open to speculation. 



If we consider the genital organs as representing the "legs" 

 of the eighth and ninth segments, then gl would represent 



*Huxley, in The Anatomj^ of Invertebrated Animals, p. 364, fig. 104, figures 

 an Aphis in which cerci are present. Whether this is supposed to be drawn from 

 an actual specimen or is only a composite figure, we are unable to state. 



tWalker, 1919, Ann. Ent. Soc. Am. XIII, p. 267-316. 



