362 W. D. FUNKHOUSER 



laterad (Plate xxxix, 10, 11). In shape the basal part is comparatively 

 straight and the distal end bends upward in a gradual curve (Plate xxxix, 

 5, 16, 18, 24) or sharply at an angle (Plate xxxix, 27, 28). The tip is 

 the most inclined to variation, and may range from a sharp, needle-like 

 point (Plate xxxix, 5, 8) to broadly angled plates (Plate xxxix, 14, 22) 

 or sharply toothed hooks (Plate xxxix, 16, 27). 



Study of the process of copulation in the living insects proves the 

 function of the styles to be that of clasping or interlocking organs, as 

 their shape would indicate. The terminal hook or angle always turns 

 upward and in some cases forward. In a few species examined, the styles 

 act in conjunction with the teeth of the lateral plates in the mating process. 



As in the case of the oedagus, the structures of the styles offer good 

 taxonomic characters and may be found useful in a number of genera. 



The sternal plate is apparently a modified abdominal sternum, but 

 its tendency to subdivision would suggest that it may be a fused or partly 

 fused pair of appendages. The plate originates at the base of the ninth 

 segment and is attached to the eighth abdominal sternum. It projects 

 first caudad and then dorsad and is the most posterior of the genital 

 organs. It may extend only a short distance upward (Plate xxxix, 7), 

 or it may extend so far in this direction as to hide the other genitalia 

 when viewed from a caudal aspect (Plate xxxix, 4, 15). As has been 

 noted, it usually shows a division down the median line. This division 

 may show only a slight notch (Plate xxxix, 4), or the separation may 

 be so apparent as to show two distinct plates (Plate xxxix, 13); but 

 in almost every case the two halves of the plate may be puUed apart 

 after boiUng in caustic potash, showing the real structure of the sclerite. 

 For systematic purposes the appearance of the plate in the complete insect, 

 rather than a theory as to its anatomical condition, is of course of more 

 practical importance. This can usually be best ascertained from a strictly 

 caudal view, and the characters most easily noted are the comparative 

 length of the plate, the shape of the upciu'ved part, and the amount 

 of sphtting at the tip. All these points show sufficient vaiiation to aid 

 in diagnosis and all are relatively constant. 



The sternal plate is usually pubescent and often covered with stiff, 

 bristle-hke hairs (Plate xxxix, 10). It is freely movable and in the 

 relaxed specimen may be pulled far downward without injury to itself 

 or to the remainder of the genitalia. It may often be examined by merely 



