48 



British Dragoujiies. 



as the insertion of the antennae. Behind this and, con- 

 sequently, in those genera in which the eyes meet, to the 

 rear of their point of junction, is the occipital region. 

 Anterior to the vertex is the frons, in front of which is 

 the post-clypeiis, or nasus, and in front of that again the 

 ante-clypens, or rhinariuin. On each side, between the 

 eye and the mouth, is the gcua, while the gida forms 

 the base of the head, and is bounded anteriorly by the 

 mentnm, or chin, which is situated at the base of the 

 labium. (See also Figs. 23 and 24.) 



The lower part of the face is occupied b}- the mouth, 

 the arrangement of which is of special importance, seeing 

 that we are dealing with a carnivorous insect. It is 

 closed above by the labnim, or upper lip, and below by 

 the labium, or lower lip. This latter is composed of three 

 pieces, the median lobe and two lateral ones. The 



Fig. 21. — Mouth-parts of ^Hschna cvanea. 



A, Labium : s.. Side I.obes ; )»., Median Lobe. B, Maxilla. 

 C, Mandible. 



former is cleft in the centre in the Agrionidcs, the 

 Cordulegastcriiice, and some Gouiphitice. In the rest it 

 is entire, although in the yEschuiitu' a line indicates the 

 fissure found in the other groups (Fig. 21, A). These 



