NEUROPTERA 



299 



measuring in wing-expanse from 40 mm. to 75 mm., vars-ing greatly 

 in size. They are nocturnal and are attracted to lights. The two 

 species can be distinguished as follows : 



PolystoEchotes piinctdtiis (Fig. 337). This is blackish, with three 

 longitudinal lines on the prothorax, and with the lateral margins of 

 this segment yellowish. 



Pig. 338. — Wings of Polystcschotes punctatus. 



Polystoschotes vittdtus. — This is pale yellowish, with a black stripe 

 on the sides of the thorax, and with the abdomen dark brown. 



The larva of neither of these species is known. This is a strange 

 fact considering the size and the abundance of these insects. 



The wings oi Polystachotes punctatus (Fig. 338) represent the type 

 of wing-venation characteristic of this family. In these wings the 

 humeral cross-vein is recurved and branched; veins Sc and Ri co- 

 alesce at the tip; the radial sector is pectinately branched; the nimi- 

 ber of cross-veins is greatly reduced; but there is in both fore and 

 hind wings a very perfect series of gradate veins. 



In these wings the development of definitive accessory veins on 

 the radial sector and the regularity of the border of marginal accessory 

 veins have reached a very high degree of perfection. 



Family CHRYSOPID^ 

 The Lacewing-Flies or Aphis-Lions 

 The family Chrysopidas includes the insects commonly known 

 as lacewing-fiies; these and their larvee, the aphis-lions, are common 



