595,78 87 



The Classification of the Day Butterflies 



{Concluded from p. 26.) 



IEECOGNISED in my studies from the first, the fact that the 

 veins or nervures may be approximately divided into two 

 groups: the movable and the stationary rods sustaining the wing 

 membrane. The veins of the first class constantly shift their 

 position and occasionally vanish. The veins of the second class 

 form part of the more durable pattern of the wing, and remain in 

 the same relative position through a single or through many groups 

 and divisions. The cubitus, and its two branches, is a stationary 

 vein, and this quality belongs also to the radius except so far as the 

 branches are concerned. The infracubital veins have in part only 

 a comparative stability. The median series belongs now, though 

 probably it did not always, to the movable veins. A summary of 

 the veins and branches of the wing may be here given for con- 

 venience of reference. 



FOREWINGS 



I. Costal nervure or vein, seldom present. 



II. Subcostal nervure, simple and constant. 



III. Radius, normally five-branched, becoming by reduction 

 three to four branched. 



IV. Media obsolete from the cross vein to the base in most 

 lepidoptera, this basal portion being only represented by a double or 

 single fold or scar, traversing the medium cell ; normally with three 

 branches, the middle one sometimes fading out in its original central 

 position as the result of the disintegration of its support, again all 

 there being drawn into the system of the Eadius or Cubitus and 

 thus preserved. 



V. Cuhitus, two-branched. 



VI. The internal fold. This, very often obsolete, becomes 

 hardly ever a vein, so far as I know, and its enumeration might be 

 thought superfluous. 



VII. The internal vein, simple and constant. 



VIII. A reduced loop at the base of VII., joining outwardly 

 this vein, sometimes prolonged, again abbreviated, oblique, sometimes 

 in a state of degeneration, sometimes wanting. 



