STOUGH : THE HACKBERRY PSYLLA. 143 



3 -f- 4. In one specimen of Psylla coryli I found that on one 

 wing the media was single instead of two-branched, but never 

 found such a case in the present species. The two lower 

 branches above mentioned are Cu 1 and Cu 2. Below this is 

 what is called the "claval suture," corresponding to the anal 

 fold (fig. 46, af). The region posterior to the anal fold or 

 claval suture is generally called the "clavus," from the corre- 

 sponding region in heteropterous wings, cl. One anal vein is 

 present; this, by a dorsal and cephalic folding over of the 

 distal half of the margin of the clavus, takes the place of the 

 costa at this point (that is, forms the posterior edge of the 

 wing here), the two veins appearing upon first observation 

 to have crossed. This condition was also observed in the 

 nymphal wing pads and in the wings of newly emerged indi- 

 viduals. 



Hind Wing (27-7). — This is more simple in venation than 

 the fore wing. The costa soon becomes weak and indefinite. 

 The subcosta is not visible except in newly emerged individ- 

 uals where the tracheae are filled with air, and the radius is 

 seen as in the fore wing, as a single vein. The media is also 

 a single vein, though in two specimens I found it two-branched 

 in one wing after the fashion of that vein in the fore wing. 

 The cubitus has two short branches. The claval suture and 

 anal vein are practically the same as those in the fore wing, 

 only there is no folding over of the posterior margin of the 

 clavus. 



The adult wings as above described are specialized by re- 

 duction, the coalescence of veins being outward. 



According to Mally's nomenclature, the common base of the 

 media and cubitus which joins the subcosta plus radius is 

 known as the "Petiolus cubite," Pc; the media and cubitus be- 

 fore branching are known as the "first cubitus" and the "sec- 

 ond cubitus," and their branches the "first, second, third and 

 fourth furcal veins." The presence of a media is not recog- 

 nized by him. 



Edwards calls the media and cubitus the "upper and lower 

 branches of the cubitus," and the "Petiolus cubite" of Mally 

 the "Stalk of the cubitus." He mentions no media. 



Woodworth (1906) adheres to a nomenclature somewhat 

 different. According to this, the media and cubitus are called 

 the "independents" which "appear as a twice-forked branch 



