NEUROPTERA. 171 



135'"™ (4-54 inches) from tip to tip, and, as a matter 

 of fact, the movements of this insect are slow and 

 uncertain as compared with the rapid motions of the 

 dragon-fly. Great powers of flight are not wholly 

 dependent upon the comparative size of the wings, 

 as will be seen in the case of the Lepidoptera (see 

 p. 187). In structure, both pairs of wings are trans- 

 lucent, with an open network of veins, the term Neu- 

 roptera being from the Greek (vevpov, nerve ; TrrepoV, 

 a wing), and signifying nerve-winged. 



The egg-mass of Corydalus is peculiar and inter- 

 esting. It averages 21""" in length, and contains from 

 two to three thousand eggs, each of which is 1.3°'" 

 long, about one-third as wide, and covered with a 

 delicate shell. The young hatch simultaneously and 

 in the night.^ 



The larva, or ^'Dobson," as anglers call it (Fig. 119, 

 a), is aquatic. The body is larger and stouter than 

 that of the adult, as is often the case with larvae, and 

 the head is similar in shape, but of a deeper color. 

 The thoracic rings are distinct and movable. The 

 abdomen has nine pairs of long appendages extending 

 from the sides (see Fig. 119, a, which represents the 

 first eight pairs) ; at the base of the first seven pairs 

 are tufts of tracheal gills (not distinctly seen in the 

 drawing ; see Comstock, Introductioji to Entomology, 

 Fig. 191). Besides these organs there are eight pairs 

 of abdominal and one pair of thoracic spiracles ; these 



1 See Proc. Amer. Assoc. Adv. Sci., Vol. XXV,, p. 275. 

 See also Zittel, Haitdbuch der Pahvontologie, Bd. II., Fig. 981, 

 for figure of the egg-mass of Corydalites, a fossil form. 



