90 



Media. Traversing the middle of the wing there is a 

 longitudinal vein which is always branched in generalized 

 insects ; this is the media. In Rhyphus the media is three- 

 branched (Fig. 2, M v J/ 2 , and J/ 3 ). 



Cubitns. The third and last of the branched veins in flies 

 is the cubitus. This vein is two-branched in Rhyphus (Fig. 

 2, O/ t and O/J. 



Anal veins. Caudad of the cubitus there is in Rhyphus a 

 single well-developed vein ; this is termed an anal vein. As 

 in more generalized insects there are three anal veins, and as 

 this is believed to be the first of the series, it is designated 

 the first anal vein (Fig. 2, \st A). A rudiment of the second 

 anal vein persists in Rhyphus j this is indicated in the figure 

 by a dotted line, at the left of the letter A. 



Designation of the longitudinal wing-veins by numbers. Several 

 writers have designated the longitudinal wing-veins by numbers. In Corn- 

 stock's Manual for the Study of Insects both the names given above and 

 numbers are used. The following table indicates the correspondence of the 

 names and numbers ; and Figure 3 represents the wing of a butterfly, with 

 the veins and cells numbered according to the system used in that manual. 



Costa = vein I. Cubitus = vein VII. 



Subcosta = vein II. 1st anal vein = vein VIII.* 



Radius = vein III. 2d anal vein = vein IX. 



Media = vein V. 3d anal vein = vein X. 



It will be observed that in the above table the numbers IV and VI are 

 omitted. At the time the Manual for the Study of Insects was published, it 

 was believed that two other longitudinal veins (the so-called premedia and 

 postmedia) were present in certain orders of insects, and the numbers IV 

 and VI were applied to these veins. It has since been determined that this 

 conclusion was based on an error. 



Certain writers number the wing veins without omitting the numbers IV 

 and VI, designating the media as vein IV and the cubitus as vein V. 



* As the anal furrow, which is described later, was supposed to represent the 

 first anal vein, it is numbered VIII in the descriptions of wings of Diptera and 

 Hymenoptera in the work cited, and the true first anal vein is numbered IX. 



