— 85 — 



the cells of the wings, according to the system proposed by 

 the writer,* each cell is designated by the name or number 

 of the longitudinal vein that normally forms its front 

 (cephalic) margin. This is illustrated by Figure 7, in which 



tiTi m, 

 n ! mi \ 



Fig. 7.— Wing of a butterfly. 



the numbers placed opposite the ends of the veins refer to 

 the veins ; the others, to the cells. 



When a cell is divided by cross-veins into two or more 

 parts, the parts are numbered, beginning with the proximal 

 one. Thus in the wing of Leptis (Fig. 8) cell I is divided 



vn>+ix 



Fig. 8.— Wing of Leptis. 



by a cross- vein. In this case the first part (not numbered 

 in the figure) is 1st cell I ; and the second part is 2d cell I 



* Evolution and Taxonomy, p. 93. 



