STATES OF INSECTS. (Imago. 315 
oO 
and others, the reverse of this takes place*. Where 
these organs in both sexes are toothed at the apex, they 
often vary in the number of teeth. Thus, the female of 
Megachile centuncularis has four teeth at the apex of its 
mandible, while the male has only two’. In M. Wil- 
lughbiella, though the mandibles of both sexes have four 
teeth, yet those of the male are sharp, and the two external 
ones the longest; while those of his mate are obtuse, and 
all nearly equal in length*. In Anthidium manicatum, 
the former has only three teeth, while the latter has five‘. 
The differences in this respect in the hive-bee have 
been before noticed; those of the humble-bees (Bombus) 
are strikingly distinguished from each other; the female 
mandible being very stout and wide, constricted in the 
middle, and furrowed on its outer surface; and the male, 
on the contrary, very slender at the apex, dilated at the 
base, and without furrows *. 
Of all the organs of the head, none seem so little sub- 
ject to sexual variation as the under-jaws (mazille)s. I 
can bring forward only one striking instance of it, and 
some degree of doubt rests even upon that. In the genus 
Nemognatha the maxille of the male are elongated, 
narrow, setiform, and often involute or spiral, like those of 
a bee or a butterfly. But that this is peculiar to the males 
is at present only surmised". I possess several species of 
@ Mon. Ap. Angl.i. Melitta**. a. t. i, f. 6.9.7. g. and **. b. 
t. tif. 3..9.4..¢. 
Bott. to Vile fe hd. DDR. o. Stat. Wilt. 9. 9. Lee. 
Si Aphee s. C. 2, 0.6 IXaf- 6: Fd. a 
See above, Vor. II, 123. Note”. 
£ Mon. Ap. Angl. ubi. supr. ¢. xiii f. 13. 9.14. g. 
® MacLeay Hor. Entomolog. 4—. 
h N. Dict. d’? Hist. Nat. xxii. 488. 
