NERVE-WINGED INSECTS. 377 



It has not only the art of lengthening, but also of widening, its 

 little tenement. It actually makes a slit from end to end, which 

 it fills up, and makes it as complete and secure as it was before 

 the opening was made. Three weeks after it becomes a chrysalis, 

 it comes forth a moth of silvery grey color. 



CHAPTER XVI. 



DIVISION II.— INVERTEBRATES. 



CLASS v. — INSECTS. 

 ORDER IV. — NERVE -WINGED INSECTS. 



This order also has four wings, membranous, naked, and 

 so interspersed with delicate veins, that they have the appearance 

 of a beautiful network. The tail is not furnished with a sting, 

 but that of the male has frequently a kind of forceps or pincers. 

 They comprise the Ephemera, the Dragon Fly, the Ant-lion, White 

 Ants, etc. Some undergo a complete metamorphosis, others only 

 a partial change of form. 



Ephemerae, or Day-Flies — It is remarkable, that the 

 larvx of the ephemerae flies live in the waters for the space of 

 three years. When the regular time of their change arrives, it is 

 effected in a few moments. Then it rises to the surface of the 

 water, and becomes a winged chrysalis. It flies to the nearest 

 resting-place, and in a moment it undergoes a second change, anc 

 becomes a perfect ephemera. In this state it continues no long'ji 

 than half an hour. It flutters and dances during its short exiht^ 

 ence in the sunbeams, and after enjoying a few minutes of gaif »y 

 and pleasure, its exintence is brought to a close. 

 32* 



