244 



THE WINGS OF PLECOPTERA 



between the subcostal trachea and the costal margin of the wing and in the 

 area between the subcostal trachea and the radial trachea. In some cases 



^:>5i, . 



Fig. 244. — Wings of a nymph of Nemoiira (From C. & N.). 



at least, these trachese do not arise from the same trunks as do those 

 tracheae that precede the wing veins.* 



(c) THE CLASSIFICATION OF THE PLECOPTERA 



As it is necessary in the following discussion of the wings of the Ple- 

 coptera to refer to the divisions of the order, and as the classification adopted 

 here has not been included in any of the text books, I give a brief outline of 

 it. It is the classification proposed by Dr. Gtinther Enderlein ('09). 



Enderlein divides the order Plecoptera into two suborders, the Holog- 

 natha and the Systellognatha. In the former he includes three families; 

 in the latter, two, as shown by the following table : 



r Fam. Gripopterygidas 

 Suborder Holognatha \ Fam. Capniidee 



I Fam. Nemouridas 

 / Fam. Pteronarcidae 

 I Fam. Perlidas 



Suborder Systellognatha 



*I have been greatly aided in my study of the trachcation of the wings of the Plecop- 

 tera by the opportunity of examining an extended .series of jihotographs and sketches 

 of the wings of nymphs made by Miss Lucy W. Smith, which she kindly jjlaced at my 

 disposal and which supplement in several important particulars those made by Dr. 

 Needham and myself. 



