MECOPTERA 



551 



The prothorax is small ; the mesothorax and metathorax are large. 

 The legs are long and slender; the tarsi are five-jointed; in some 

 genera there are two tarsal claws, in others only one. 



The wings are membranous, and are usually long and narrow, but 

 in two genera, Notiothauma and Merope, the representatives of which 

 are very rare insects, the wings are comparatively broad. In the genus 

 Boreus the wings are vestigial or wanting. 



The type of the venation of the wings in this order is well shown 

 by the wings of Panorpa (Fig. 676). In the species figured here, the 



^i_^. 



Fig. 676. — Wings of Panorpa. 



number and arrangement of the wing-veins in the fore wings is that 

 of the hypothetical primitive type, with the addition of a considerable 

 niimber of cross- 

 veins, and an ac- 

 cessory vein on 

 vein R2. The same 

 is true of the hind 

 wings except that 

 each of the branches 

 of cubitus anasto- 

 moses with the ad- 

 jacent vein; that is, 

 vein Cui anasto- 

 moses with vein M, 

 and vein'Cu2 with 

 the first anal vein 



Fig. 677. — Base of hind wing of Panorpa. 



