620 EXTERNAL ANATOMY OF INSECTS. 



wing- are less distinct and rather cartilaginous ; the ner- 

 vures of the Anal Area often terminate in a transverse one 

 that there forms the segment of a circle a ; the inner base 

 of this circle is ligament connected with the postfrcenum h '. 

 In the Homopterou,s Hemiptera the three axes may be 

 readily traced, but the humeral plate, with which they all 

 are connected, is more irregular in shape, and in Fulgora 

 longitudinal, with an angular surface; in this Order the 

 nervure, in some cases consisting of cartilaginous rings c , 

 in which the franum and postfrcenum terminate in the 

 tegmina and wings, is attached posteriorly to the ligament 

 of the Anal Area. In the Heteropterous section the three 

 axes are evident, but the humeral plate is not easily made 

 out. In the Libellulina the axes of the Costal and Inter- 

 mediate Areas are the coloured broad plates at their base, 

 formed by the dilatation of their nervures ; that, however, 

 of the Anal is not dilated, but forms one nervure, in the 

 primary wing, with \hefr<znum, and in the secondary with 

 the postfrcenum. Having given you this clue to trace the 

 axes in those tribes in which they are most conspicuous, 

 it will assist you in searching for them in the remain- 

 ing Orders, in all of which they may be traced, except 

 perhaps in those minute Hymenoptera whose wings have 

 solely the costal nervures ; probably in these there is only 

 one axis. In the Lepidoptera and Hymenoptera a cir- 

 cumstance connected with the present head is observable, 

 which is not to be discovered in the other Orders: these 

 are the tegtiUe or base-covers, which appear intended to 

 defend the base of the anterior wings. They are con- 

 cavo-convex scales, which in the Lepidoptera are large 



a Plate XXVIII. Fig. 9. a. >> See above, p. 572. 



e Ibid. p. 560. and Plate XX VIII. Fig. 11. a. 



