1913] Wmg Veins of Membracidce 95 



they are often some distance apart and connected by a strong 

 cross-vein. ^"^ The explanation to the disappearance of costa 

 and subcosta which causes this condition — which is of course 

 the more generaHzed one — is probably that the median part 

 of the wing, having an advantageous blood supply, has devel- 

 oped to such an extent as to crowd the cephalic region, causing 

 radius to move over into that part of the wing usually occupied 

 by costa and subcosta, and forcing these trache£e out of existence. 



Media is typical (Fig. 28), branching in about the center 

 of the wing into M1+2 and M3+4 which continue their respective 

 courses toward the tip, there to turn along the marginal line 

 as in the fore wing. 



Cubitus likewise presents the same condition that it does in 

 the fore wing (Fig. 29). At times the tracheae representing Cui 

 and Cu2 respectively may be traced side by side for some 

 distance back into the wing, but in no case do they separate. 



First anal differs from the front wing in being stronger and 

 not paralleling the suture. The wing membrane at this point 

 in the hind wing is smooth and firm. 



Second and third anals are usually coalesced to form one 

 vein in the adult hind wing, although the individual tracheae 

 are to be seen in the nymphal structure. Occasionally these 

 two veins separate to form the cell 2nd A as in Ceresa bubalus. 



This is the normal venation. Some slight modifications can 

 be found in a few genera. In Smilia, Cyrtolohus, Xantholobus, 

 Ophiderma, and others, the characteristic cross-vein between 

 R4+5 and Mi+2 is lacking, these two veins anastomosing as in the 

 front wing. In other respects the hind wings vary far less 

 among the genera and species than in the fore wing, even in 

 minor details. In many cases they are identical and it has 

 been' hard to find forms with differences marked enough to be 

 worth figuring. It will be remarked in the figures that in shape 

 and general appearance the agreement is quite noticeable. 



36. See figures of Carynota mera, Thelia himaculata, Glossonolus crataegi, 

 Telemona ampelopsidis, Archasia beljragei, and Heliria scalaria. 



