— 8o — 



the numbering of the veins in Figure 2. By this system 

 the principal veins are numbered with Roman numerals, 

 and the branches of a vein are designated by Arabic sub- 

 numbers. Thus the branches of vein III are designated as 

 IIIi, III2, III3, III4, and III5, respectively. 



The correspondence of the numbers and the names ap- 

 plied to the wing-veins by the writer is shown in the follow- 

 ing table : — 



Costa = vein I. 



Subcosta = vein II. 



Radius = vein III. 



Premedia = vein IV. 



Media = vein V. 



Postmedia = vein VI. 



Cubitus = vein VII. 



Anal furrow = vein VIII. 



Other anal veins = veins IX, X, et at. 



In most of the orders of insects there is obviously no 

 longitudinal vein between radius and media, and none be- 

 tween media and cubitus. In numbering the veins of the 

 wings of such insects, the numbers IV and VI, which have 

 been applied to the premedia and postmedia of May-flies, 

 are omitted. This is done in order that homologous veins 

 shall bear the same numbers in all orders of insects. 



It is often necessary to refer to particular cross-veins ; 

 this can be done by using the numbers of the two veins 

 connected by the cross-vein ; thus a cross- vein extending 

 from vein I to vein II may be designated as vein I — II ; 

 and one extending from vein III to vein ,V, as vein III — V. 

 In reading these expressions the word to is substituted for 

 the dash, as " vein III to V." 



When there is more than one cross-vein between two 

 longitudinal veins they may be numbered as follows : 1st 

 vein III — V, 2d vein III — V, etc. In lettering a figure the 



