24 THE RICE GRASSHOPPER 



to the posterior border of the ninth abdominal segment, 

 while the lower pair are two minute protuberances resting 

 on the posterior border of the eighth segment (see Figs. 1 

 and 2). 



In the second instar (Figs. 3 and 4) the lower pair has 

 greatly enlarged and taken on a triangular form, while the 

 upper pair show^s only a comparatively slight growth. 



In the third instar (Figs. 5 and 6), the lower oviposit- 

 ors have grown backward so as to cover a large part of the 

 ventral portion of the ninth segment. In the upper pair, a 

 very interesting cliange has taken place. From the inner 

 edges of the two, a pair of lobes have been partially separat- 

 ed. The division is not, however, yet complete as the 

 dividing line or furrow does not yet reach the posterior 

 border of the ninth segment. An examination of the pre- 

 vious instar shows no sign of this division. 



In the fourth to seventh instars, we find a gradual 

 growth backward of the two pairs of ovipositors till their 

 ends come to lie at the posterior end of the body (see 

 Figs. 7-11). At the same time, there is a gradual separation 

 of the interior lobes from the upper pair. These lobes come 

 to lie beneath and between the upper pair of ovipositors 

 and to form a forked structure (the furcula supravulvalis) 

 lying just above the female genital opening. 



The development of the ovipositors in this form, as 

 described, is probably representative for the whole group of 

 short-horned grasshoppers (Acridiida^). It also appears 

 to bear a general similarity to the development of the 

 much more conspicuous ovipositors found in the grouj) of 

 long-horned grasshoppers (LocustidaB).^ 



In the sixth instar appears another structure which 

 also functions in the act of egg-laying — the so-called egg- 

 guide. This is a minute, pointed, awl-shaped structure 

 which grows out from the posterior border of the eighth 

 abdominal segment between the lower pair of ovipositors 

 and which aids in directing the egg between the upper 

 pair of ovipositors. The appearance of the ovipositors in 

 the adult and their method of working has already been 

 explained and illustrated. 



In the case of the male grasshopper, the development 

 of the external structures at the posterior end of the body 



1 In this connection yifZe Dewitz, Uber Bau und Entwicklung desStachels undder 

 Legescheide einiger Hymenopteren und der griinen Heuschrecke, Zeitschr f. wiss Zool. 

 XXVI, 1874, pp. 74-200. 



