DRAGON-FLIES. 39 



small. The mesothorax and metathorax about equal. The upper 

 surface is not fixed as in other insects but the parts are movable, 

 which gives the wings great freedom. 



In their early stages they live in water, and (like the adult) are 

 carnivorous, feeding on other insects, snails, etc. 



The larva possesses an extraordinary-developed labium. "When 

 at rest this is folded beneath the head, the front part of it forming 

 a mask ; but is jointed and can be darted forward with great rapidity 

 when the insect seizes its prey with the terminal toothed appendages 

 (1410). 



The Odonata have been arranged in two divisions : — 



Div. I. — Anisopteea, in which the front and hind wings are 

 more or less unlike, the hind pair enlarged near the base. This 

 division contains the families Libellulidce,, Corduludce, Gompkidce, 

 Cordulegasfridm and ^schiidce.. The characters of these families 

 are chiefly in the form of the head and the neuration of the wings 

 as explained in the labels exhibited. 



They fly with the greatest rapidity. 



Div. II. — Zygopteea in which the wings are alike, both pairs ^ aU % 

 equally narrowed at the base. This division consists of two families, 

 the Calopterggidcc (1439-1446) and Agrionidce (1447-1453). 



Among these are some of the most brilliantly coloured insects 

 known. Unlike the Anisoptera they are comparatively slow fliers, 

 and are generally seen fluttering about the herbage at the sides of 

 ponds. 



Dragon-flies have been found plentifully in a fossil state in 

 tertiary strata, including species of Libellula and Agrion, both 

 larvae and perfect insects, differing but little from those of the 

 present day. Some large species have also been found as far back as 

 the Lower Lias. 



The remains of an enormous insect, Meganeura mongi, measuring 

 two feet in expanse of wings has been found in the Carboniferous 

 strata. It has four equal wings, and is evidently not far removed 

 from the Dragon-flies. The neuration of the wings differs, however, 

 in some important characters, and the shape of the body, so far as 

 can be seen, is different. Its place appears to be between the May- 

 flies and Dragon-flies. 



A drawing of one of the wings, natural size, is exhibited. There 

 are no specimens in the Museum collection. 



