NMUBOPTEHA. 



365 



the Cinura, to which belong the genera Cainjjodea (Fig. 



324), Lepisma, and Machilis. 



In these Tliysanura there is no 

 spring, but the tail ends in two or 

 three bristles ; and in Machilis, 

 the highest form, there are com- 

 pound eyes ; in all there are 



A Podiirau (Tomocerus) and its scales. Mucli enlarged. 



jointed abdominal appendages, which 

 structures are unique among Hexa- 

 podous insects. Campodea Ameri- 

 cana Packard is a small white slender 

 form, with long, many-jointed an- 

 tennje, and two long, slender jointed 

 caudal appendages. It lives under 

 stones, and G. Cookei Packard lives 

 in Mammoth Cave. 



Order 2. Neurojjt "ra. — This group 

 of net-veined insects is interesting 

 from the fact that the existing 

 families are widely separate, owing 

 to the geological extinction of inter- 

 mediate links found fossil in the 

 Devonian and Carboniferous strata. 

 The mouth-parts are free, adapted 

 for biting ; the wings are broad, the 

 hinder pair sometimes larger than 

 the front pair, and both pairs are finely net-veined. 



The 



