J. H. MERRILL 119 



of Megarhyssa lunator, the transverse cubital nervure is lost. 

 As a result of this, the so-called cubito-discoidal cell includes 

 not only the first, but the second cubital cell, and the cells spoken 

 of by Cresson as the second and third cubital cells are in reality 

 the third and fourth cubital cells. The nervures (f.) and (g.) 

 though called the first and second transverse cubitals are actually 

 the second and third. 



In the hind wing the nervures and cells are fewer in number 

 than in the fore wing. The subcostal nervure runs outward 

 from the base of the wing for nearly two-thirds the length of 

 the latter, joining the costa at a small notch in the costal margin. 

 From this point the radial or marginal nervure passes obliquely 

 outward and backward to the outer margin some little distance 

 behind the apex. Behind the subcostal lies the externo-medial 

 nervure, which passes outward, gradually diverging from the 

 former till intersected by two cross nervures. Bej'ond the inter- 

 section it continues to the hinder margin, this portion being 

 termed the discoidal nervure. Behind the externo-medial 

 nervure is a third longitudinal nervure w^hich extends from the 

 base of the wing to its hinder margin, which it reaches a short 

 distance before the middle of the margin. The externo-medial 

 nervure is intersected in front by the cubital nervure, the two 

 uniting at nearly right angles. The latter abruptly turns out- 

 ward, however, and gradually backward and reaches the hinder 

 margin of the wing about half w^ay between the ends of the dis- 

 coidal and marginal nervures. At about its middle, it is joined 

 by the hinder end of the transverse cubital nervure which passes 

 forward, then outward, then forward and unites with the mar- 

 ginal nervure near its middle. From the point of intersection 

 of the externo-medial and cubital nervures the transverse medial 

 originates, extending backward and inward and joins the anal 

 nervure a short distance before the latter reaches the wing 

 margin. 



The cell lying between the costa and the subcostal nervure is 

 known as the costal cell: that in front of the marginal or radial 

 nervure, as the marginal or radial cell : that bounded in front by 

 the costal and part of the radial nervures, behind by the externo- 

 medial and the inner part of the cubital nervures, and externally 

 by the transverse cubital nervure — the largest cell of the wing — 



TRANS. AM. ENT. SOC, XLI. 



