450 EXTERNAL ANATOMY OF INSECTS. 



ally more slender from the base to the summit 3 : a tribe 

 of small water-beetles (Haliplus), the saw-flies {Ten- 

 thredo L.), and several other Hymenoptera, have them 

 thickest in the middle b . Their most important part, 

 however, and that which varies most in form, is the ter- 

 minal joint: — of this I have already related some singular 

 instances c , and shall now describe a few more. This 

 joint is sometimes acute, at others blunt, at others trun- 

 cated: in figure it is ovate, oblong, obtriangular, hatchet- 

 shaped, lunate, transverse, conical, mammillate, subulate, 

 branched, chelate, laciniate, lamellate, &c. &c. d : terms 

 which I shall more fully explain to you hereafter, and 

 which I only mention here to show the numerous varia- 



a Kirby Mon. Ap. Angl. i. t. x. Apis. **. c. 2. l.f. 3. a. and **. d. 1. 

 f.l.d. ' 



b Clairv. Ent. Helvet. ii. t. xxxi./. super, b. Mon. Ap. Angl. i. t. xiv. 

 f.l.k.f.3,5.c. 



c See above, p. 317. 



d Plate XXVI. Fig. 1. As the very remarkable maxillary palpi 

 of that extraordinary Coleopterous genus Atractocerus seem not to 

 have been so fully described as they deserve, I shall give here a mi- 

 nute detail of their composition. They consist of four joints : the 

 first is wide and short, and somewhat platter-shaped; the second is 

 much smaller and shorter : the third is concavo-convex, or shaped 

 like a shallow bowl : towards the breast this joint is elevated, and 

 on the elevated edge sits the last joint, which is longer than all the 

 rest taken together. In my specimen it points towards the breast ; 

 its under side is entire and slightly curved, but in the upper side are 

 two rows of lamellae (b), placed alternately nine on each side, with an 

 odd one at the end : these lamella? are full of minute papillae, and 

 furrowed on the side next the mouth. From between the first pair 

 a slender exarticulate hairy branch or appendage emerges («), which 

 forms nearly a right angle with the main stem. The labial palpi 

 appear to consist of three joints ; the two first very short, and the last 

 large, ovate, and acute. This description is not taken from A. necy- 

 daloides, but from a Brazilian species more than five times its size, 

 which I have named A. Gigas, 



