94 John He7iry Com stock 



In certain special cases special names may be desirable. 

 Thus in the Lepidoptera the cells formed by the anastomosing 

 of the branches of radius are commonly known as the accessory 

 cells, which is a very convenient term. And cell III + V is 

 universally known as the discal cell. In some of the more 

 generalized moths a cell is formed within the discal cell by a 

 forking of media : this has been termed the interpolated cell 

 (Figs. 12, 22, 27). 



In those orders where there are transverse veins, each of the 

 cells between two longitudinal veins is divided into a series of 



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Fig. 33. — Fore wing of Danais, illustrating the nomenclature of the 

 veins and cells. The numbers placed opposite the ends of the veins 

 refer to the veins ; the others, to the cells. 



cells, and can be so designated. Thus the series of cells be- 

 tween veins IIIi and IIIj may be termed the first series of radial 

 cells ; and the members of such a series can be numbered. If 

 one should speak of the peculiar form of the third cell in the 

 second radial series, there need be no difficulty in determining 

 the cell indicated, even by one who had not made a special 

 study of the order to which the insect in question belongs. 

 Heretofore it has been necessary for the student to learn a dis- 

 tinct nomenclature for each order, and in some cases for each 

 family, studied. 



In concluding this part of this essay I wish to refer to two 

 curious methods of specialization that have interested me 



