ZOOLOGY. CO 5 



COHORT II. CRUSTACEOUS FLIES DICTYOPTERA. 



3522. Four wings, with longitudinal and numerous 

 transverse veins, the anterior pair being mostly leathery in 

 texture ; eyes mostly smaller than head. 



Here belong the Neuroptera, Orthoptera, and He- 

 miptera. 



The metamorphosis is tolerably imperfect, and the 

 larvae have never more than three pairs of thoracic feet, 

 and therefore correspond no longer to the Worms, but to 

 the Crabs, where the number of the feet has been already 

 more determined. Many also strikingly simulate the 

 Crustacea. 



In all three families also the pupa runs about, eats, 

 and has rudiments of wings. 



The abdominal rings are mostly horny and hairless. 

 The spiracula lie upon the upper margin. 



The eyes are generally much smaller than the head, 

 and may therefore, in comparison with those of the pre- 

 ceding and subsequent groups, be said to be of middling 

 size ; the simple eyes have for the greatest part disap- 

 peared. Meanwhile the first family displays large eyes, 

 the second eyes of a middling size, the third small eyes. 



They divide like their antetypes, the Crabs, into three 

 orders. 



Order 4. Crab-Flies Neuroptera. 



3523. All the wings alike and membranous ; maxillae 

 with mostly large eyes ; abdomen soft. 



These Insects which, on account of their delicate wings, 

 are known with us by the name of Flohrfliegen, live 

 mostly upon flesh, and many of them by capturing living 

 prey. Many undergo a short pupa stage. Many live in 

 the water and have, too, branchiae, whereby they strikingly 

 remind us of the Crustacea, especially the Branchiopoda. 



Like the Crustacea, or in accordance with the two 

 first cohorts of their class, they divide into two families. 



Fain. 1. Tracheopteroid Neuroptera, Nagbolden. 



Do not subsist by rapine, but gnaw slowly animal and 

 vegetable matters ; many also as flies eat no longer. 



