152 The Classification of Insects 



is closed at the end by too small cross nervules (the 

 discocellulars), which make an obtuse angle with 

 each other. But in the forewing of Chrysophanus 

 the first median branch is fused with the radial for a 

 great part of its length, while the upper discocellular 

 nervule is absent. These differences, though they 

 may seem exceedingly slight, are found to hold 

 constantly throughout a vast number of species. 

 Moreover, such characters, not 

 being affected by the insects' 

 V^ manner of life, are specially 

 Y'*^« valuable in indicating relation- 

 ships, since they have presumably 

 ^' been transmitted through many 

 'generations with very little 

 vu change. 



Family. — In the main features 



of their structure, however, 



Chrysophanus and Polyommatus 



are closely alike. With the 



'"^i exception of the distinguishing 



'V, points mentioned above, they 



agree in the neuration of the 



wings, the even spacing of the 



various nervures as well as the 



of the last radial 



87, iiis) at the 



Vll 



Fig. 87.— Neuration of wings tCrmmatlOn 

 o{ Lyaena. II. sub-costal; 1 t. / c 



III. radial; IV. median ; Dranch (llg 



V. cubital; vi.-viii.anai ej^f^gj^g tip of t h 6 forewing 



Twice natural 



size. From Grote, Natural being speciallv characteHstic. If 



Science, vol. 12. • 1 • 1 r- 1 



we examine their legs, we nnd 

 that all three pairs are developed in both sexes, though 

 the front pair are feebler in the male than in the 

 female. Turning to the immature stages, the cater- 

 pillar is, in both genera, short, stout and hairy, in 

 shape somewhat resembling a wood-louse, while the 

 pupa is rotund in form and covered with hairs or 



