190 INSECTA. 



on the thorax; abdomon ensiform, sometimes brown, and at 

 others slate coloured, with yellowish sides *. 



iEsHNA, Fab. 



The ^shnae resemble the Libellulae proper in their mode of bear- 

 ing their wings, and in the form of their head, but their two poste- 

 rior ocelli are jjlaced on a simple transverse elevation in the form of 

 a carina. The intermediate lobe of the labium is also larger, and the 

 two others are distant and armed with a very stout tooth and spini- 

 form appendage. The abdomen is always narrow and elongated. 



The body of the larvae and the nymphs is also more elongated than 

 that of the Libellulae in the same states. The mask is flat, and the two 

 pincers are narrow, and have a small movable nail at the extremity. 

 The abdomen is terminated by five appendages, but one of them is 

 truncated at the end. , 



M. gru7idis ; Libellula grandis, L. ; Roes. Insect. Aquat., 

 VI, iv. One of the largest species of this family, being nearly 

 two inches and a half in length ; fulvous-brown ; two yellow 

 lines on each side of the thorax ; abdomen spotted with green or 

 yellowish ; wings iridescent. It darts with amazing rapidity 

 over meadows, and along the shores of rivers, &c., pursuing flies 

 in the manner of the Swallow f. 



Agrion, Fab., 



Where the wings are elevated perpendicularly when at rest, the 

 head is transversal, and the eyes are distant. 



The form of the labium is analogous to that of the .^shnee, but the 

 intermediate lobe is divided in two, down to its base. The third 

 joint of the lateral lubes is in the form of a membranous ligula. The 

 antennae seem to be composed of but four joints. The forehead pre- 

 sents no vesicle, and tlje simple eyes are almost equal, and arranged 

 in a triangle on the vertex. The abdomen is very thin or even fili- 

 form, and sometimes very long. That of the females has its posterior 

 extremity furnished with serrated laminae. 



The body of these Insects, in their first and second states, is equally 

 slender and elongated, and the abdomen terminated by three fin-like 

 laminae. The mask is flat, the superior extremity of the menton- 

 niere being raised into a point in some, and forked or sloped in 

 others ; the pincers are narrow, but terminated by several dentations, 

 and resemble hands. 



A. virgo ; Libellula virgo, L. ; Roes., Insect. Aqat., VI, ix. 

 Golden-green or green-blue ; superior wings, sometimes either 

 entirely blue or only in the middle, and sometimes of a yellow- 



* For the other species, see Faliricius, Entom. Syst., and Latreille, Hist. Gener. 

 des Crust, et des Insect., XII, p. 10, et seq. ; but particularly the Monographs of 

 the Insects of this family, from the environs of Bologne, published in Latin by M. 

 Van der Linden, that Avhich he has since given on the species of Europe, and finally 

 another Monograph of European Libellulae, formiug a part of the already quoted 

 ■work of M. Toussaiut Charpeutier. 



f See the snme works. The yEshna forcipata might form another subgenus. 



