EXTERNAL ANATOMY OF INSECTS. 513 



Orthoptera, Flemiptera, &c. the articulation seems more 

 purely ligamentous. 



With regard to their substance — these organs are re- 

 gulated, in some degree, by the nature of the integu- 

 ment of the animal of which they are appendages ; in the 

 softer insects being of a softer substance than they are in 

 hard ones. The vertex of the joints, where they receive 

 the succeeding one, appears in many cases to be softer 

 than the rest of it, and especially towards the apex, often 

 papillose. The antennae are generally opaque ; but in 

 Nebria co?npla?iata, a beetle common on the sea-coast in 

 Wales and Lincolnshire, they are semitransparent. 



The situation of antennas must next be considered. 

 In this i-espect it seems necessary that they should be 

 so situated as to be under the direction of the eyes : for 

 if you examine ten thousand insects (except, as w r as be- 

 fore observed a , where there are four eyes), you will not 

 find one in which these organs are situated either above 

 or immediately behind them ; their station being always 

 either somewhere in the space between the eyes or that 

 below them. In Ptinus F. they are placed near the 

 vertex; but in Gibbium, which is so nearly related to 

 that destructive genus b , they are beneath them. In 

 many Melittcc K. they are in the middle of the space 

 between the eyes; and in many other Hymenoptera and 

 Coleoptera (Staphylinus &c), in the anterior part of it. 

 In many Lamellicorn genera, as Melolontha, Cetonia, 

 Lucanus, &c. they may be regarded as planted in the 

 lower surface of the cheek before the eyes ; but in Co- 

 pris &c, in which they are inserted further under the 



a See above, p. 49S. b Vol. If p. 231, 238, 



VOL. II T. % L 



