1913] Wing Veins of Membracida 89 



The Anal Veins 



If the interpretation of the preceding structures has been 

 correct, the remaining veins of the wing must represent the 

 anals. As a matter of fact, this works out very simply and 

 leaves little doubt regarding the homologies of the anal region. 

 It is true that the third anal often shows a forking in the nymphal 

 tracheation (Figs. 5 and 16), but this is of no particular conse- 

 quence since in a very large number of wings, of which that of 

 the cockroach may serve as an example'' °, the anal region has 

 become filled with many veins branching from or posterior to 

 the third anal. In fact, this condition (Fig. 19) homologizes 

 perfectly with the tracheation of this vein in the Cicadidae^^ 

 which family is as close to the Membracidae as any whose 

 venation has been determined, and in which, as in the Mem- 

 bracidffi, the specialization has been by reduction. A more 

 significant fact is that this condition is by no means a constant 

 one and should not be considered as typical of the family. In 

 the large majority of cases the anal tracheation is best repre- 

 sented by that shown in Figure 2. 



According to this determination, then, the first anal vein 

 arises from the base of cubitus with which stem it has been 

 brought from the main trunk. If this is true, the first anal is 

 very intimately connected with the cubital vein — so intimate, 

 in fact, that it seems almost a misnomer to call it an anal with 

 reference to the Membracidae — but that it is an anal is shown 

 by the fact that it homologizes with the first anal in the wings 

 of other insects. It represents the claval suture in the fore 

 wing and is in many forms very indistinct in appearance, and 

 the wing is weak along the line which it follows. It is straight 

 and unbranched throughout its course and is connected with no 

 cross-veins. At its tip it unites with cubitus, and the two 

 coalesce to form the marginal limiting vein of the cell M4. This 

 limiting vein, it must be remarked, is here preceded by three 

 tracheae, viz. Cui, Cu2 and 1st anal. 



Second anal and third anal enter the wing together by a 

 different stem, posterior to that of the cubitus-first anal. They 

 separate at once, forming a large and clearly defined cell, only 

 to coalesce again after about one-third of their course has been 



30. Wings of Insects, p. 773. 



31. Wings of Insects, p. 249. 



