48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 



superieures, inferieures and internes. The ventral pair are the first 

 valvulae, as designated in the present paper, the inner pair the second 

 valvulae, and the dorsal pair the third valvulae. In Gryllidae and 

 Acrididae the inner, or second, valvulae are rudimentary, and the 

 functional part of the ovipositor thus consists of only two pairs of 

 valvulae. Hence, it must be observed that the four-valve ovipositor 

 of these insects differs from the four-valve ovipositor of Thysanura, 

 Hemiptera, and Hymenoptera in that the shaft is formed of the first 

 and third valvulae, while in the latter groups it consists of the first 

 and second valvulae. The first valvifers are always displaced posteri- 

 orly in the Orthoptera and closely associated with the ninth segment ; 

 the second valvifers are never distinctly differentiated from the third 

 valvulae. 



^Eppfc 

 -Cer 



VlllStn iVlf iVl 



Fig. 12." — Female nymph of Scudderia. 



Dorso-pleural line of abdomen marked by a fold (a-a) ; ovipositor with small 

 basivalvular sclerite {hv) at base of first valvula (iF/) ; epiproct (Eppt) par- 

 tially surrounding base of cercus (Ccr). 



The six-valve type of ovipositor is typically developed in Gryllo- 

 blattidae and Tettigoniidae, but the basal parts of the organ are some- 

 what weak in these families, and in structure they are scarcely repre- 

 sentative of that of the highly perfected basal mechanism of the ovi- 

 positor of Gryllidae. A brief study of a typical form, such as Scud- 

 deria, however, will serve as an introduction to the more detailed de- 

 scription of Gryllus to follow. 



The abdomen of Scudderia (fig. 12) presents a wide membranous 

 area on each side in which the spiracles are located. A prominent 

 groove traversing the lower part of the membrane marks the dorso- 

 pleural line {a-a), which posteriorly extends above the basal plates of 

 the ovipositor. The spiracles lie in the laterodorsal, or paratergal, 

 region of the membrane {patg) above the dorso-pleural line. The 

 eighth, ninth, and tenth terga are distinct, and the epiproct {Eppt) 

 is well developed. The eighth sternum (VlllStn) forms a small 



