208 Annals Entomological Society of America [Vol. XV, 



smaller and more obscure. In the adult the py gofer forms a 

 ring; from its medio-ventral edge arises two small, laterally 

 flattened spines; a pair of moderately small, flattened genital 

 styles arise near the ventral margin, with a more or less 

 chitinous wall, the diaphragm, dividing them from the 

 aedeagus which is subcylindrical, flattened laterally, with the 

 orifice at the apex on dorsal aspect, with two spines near the 

 orifice. A chitinization of the body wall connects the base of 

 the aedeagus with the base of the anal segment, and there is a 

 chitinous connection between the base of aedeagus and the base 

 of the genital styles. 



If we dissect out the immature male from the nymphal 

 skin we find that the body wall at the base of the aedeagus is 

 invaginated, but the genital styles are not carried with it, 

 there being a fold of the body wall between them, (Fig. 19, dia). 

 It is this fold which forms the diaphragm of the adult. At an 

 early stage of development the ^deagus is a simple tubular 

 body with the opening slightly before the apex; the genital 

 styles are proportionally short and flat and the two processes 

 on the ventral margin of pygofer (gl) are relatively large. (Figs. 

 15, 16 and 17). At the stage shown in Figure 19 they are 

 more than half the length of the genital styles. 



In most of the Delphacidae there is no trace of gl in the 

 fully developed pygofer; in a few there is a single median 

 process, but the genus Perkinsiella has a pair of processes 

 which varies in shape and size in each species. The genus 

 Pissonotiis shows gl very well developed (Fig. 20). Among 

 other fulgorids gl are often well developed (i. e., Olonia 

 picea, Eurybrachidae and Eury?2omeus gramilatis, Achilidas). 



Among the thousand and more genera of the Fulgoroidea 

 the differences of aedeagus are very great, but they can be 

 reduced to three sub-types, which we will refer to as Tettigo- 

 metroid (A), Delphacoid (B) and Flatoid (C). The Tettigo- 

 metroid, for other reasons besides the type of male genitalia, 

 we consider as the most primitive type of fulgorid. In the genus 

 Tettigometra the pygofer is of the Cercopid type. In Hilda 

 breviceps gl are incorporated into the pygofer; the periandrium 

 is large and bulb-like and the aedeagus very short, the con- 

 junctiva being distinct; the penis-styles apodemes are well 

 developed. The medio-ventral margin of pygofer is produced. 



