HEXAPODA. 



The principal veins may be designated 'by numbers as well 

 as by names ; the following table indicates the correspondence 

 of the names and numbers : 



Costa = vein I. 

 Subcosta = vein II. 

 Radius = vein III. 

 Media = vein V. 



Cubitus = vein VII. 

 1st anal vein = vein VIII. 

 2d anal vein = vein IX. 

 3d anal vein = vein XI. 



It was formerly believed that in certain insects three other 

 longitudinal veins were present ; these were numbered IV, VI, 

 and X respectively ; hence these numbers are omitted in the 

 above table. 



At the time the first edition of this book was written, it was 

 thought best to designate the veins by numbers; and conse- 

 quently numbers are used in the following pages much more 

 generally than are the names of the veins. But owing to a 

 lack of uniformity in the numbering of the veins by different 

 writers, it is now clear that the names are to be preferred. In 



3d A 



2d A 



FIG. 79. Diagram representing- the typical arrangement of the wing-veins, includ- 

 ing the four more important cross-veins : //, humeral cross-vein ; r-m, radio- 

 medial cross-vein ; m, medial cross-vein ; m-cu, medio-cubital cross-vein. 



the lettering of figures abbreviations of the names can be used 

 as is done in Figure 79. 



The divisions of a branched vein are numbered, beginning 

 with the one nearest the costal margin of the wing ; and 



these numbers are indicated by sub-figures. For example, 

 G 



