EXTERNAL ANATOMY OF INSECTS. 44.9 
Euglossa, wild bees, they are setaceous, growing gradu- 
ally more slender from the base to the summit? : a tribe 
of small water-beetles (Haliplus), the saw-flies (Serrifera), 
and several other Hymenoptera, have them thickest in 
the middle>. Their most important part, however, 
and that which varies most in form, is the ¢ermznal joint : 
—of this I have already related some singular instances °, 
and shall now describe a few more. This joint is some- 
times acute, at others blunt, at others truncated: in 
figure it is ovate, oblong, obtriangular, hatchet-shaped, 
lunate, transverse, conical, mammillate, subulate, branch- 
ed, chelate, laciniate, lamellate, &c. &c.4: terms which 
I shall more fully explain to you hereafter, and which 
I only mention here to show the numerous variations 
* Kirby Mon. Ap. Angl.i. t. x. Apis **.c. 2. 0. f. 3. a. and **, d. 1. 
Ge le. 
> Clairv. Ent. Helvet. ii. t, xxxi.f. super.b. Mon. Ap. Angl. i. t. xiv. 
FARES: b:'¢ © See above, p. 316. 
4 Prate XXVI. Fic. 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 lamellz (4), placed alternately nine on each side, with an 
odd one at the end: these lamellz are full of minute papilla, and 
furrowed on the side next the mouth. From between the first pair 
a slender exarticulate hairy branch or appendage emerges (a), which 
forms nearly a right angle with the main stem. The Jadial 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 4. 
necydaloides, but from a Brazilian species more than five times its 
size, which I have named A. Gigas. 
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