J. H. MERRILL 117 



on its inner margin, the discoidal nervure on its front and outer 

 margins, and the anal nervure on its hinder margin, is the second 

 discoidal cell. The cubital nervure extends outward from the 

 point where the discoidal nervure bends abruptly backward, and 

 becomes lost a short distance before the outer margin. About 

 the middle of the marginal nervure arises a cross nervure which 

 passes backward and joins the cubital at about its middle. This 

 nervure has been termed the first transverse cubital, and forms 

 the outer margin of the very large, somewhat triangular cell 

 lying behind the base of the stigma, called the cubito-discoidal 

 cell. A short stump of a nervure projecting from the cubital 

 into the cubito-discoidal cell is called by Cresson an ''abbreviated 

 cubital nervure." The real significance of this nervure will be 

 discussed later. A short distance external to the first transverse 

 cubital is another cross nervure, the second transverse cubital. 

 The relation of these two nervures differs greatly, their anterior 

 ends may be close together on the marginal nervure, while their 

 posterior ends are some distance apart. These nervures enclose 

 the areolet or second submarginal cell. In some cases, the anterior 

 ends of the two transverse-cubital nervures are united for about 

 half their length. In this case, the areolet is said to be petio- 

 lated. Occasionally, the second transverse cubital is lost or 

 reduced to an abbreviated stub, in which case, the areolet is 

 absent. The presence or absence of an areolet which has here- 

 tofore been used as a generic character, is not even a specific 

 one, as both conditions have been found to occur in the same 

 species. 



The second transverse cubital nervure forms the inner margin 

 of the third submarginal cell which extends outward to the outer 

 margin of the wing. Its front border is formed by the outer 

 half of the marginal or radial nervure, and its hinder border 

 by the outer portion of the cubital nervures. Between the 

 cubital nervure and the internal margin of the wing, extending 

 nearly to the outer margin from about the middle of the back- 

 wardly turned portion of the discoidal nervure, is the subdiscoidal 

 nervure. That portion of the discoidal nervure between the 

 cubital and subdiscoidal nervures is the first recurrent nervure, 

 according to Cresson, though here described as part of the dis- 

 coidal. The second recurrent is a somewhat curved nervure 



TRANS. AM, ENT. SOC, XLI. 



