422 EXTERNAL ANATOMY OF INSECTS. 
chafer occasionally found on the coast of Kent. In some 
it is covered with excavated points; in others it is quite 
smooth. In numbers, as in the Predaceous beetles, both 
labium and mentum are perfectly naked; in others, as in 
the common cockchafer, they are hairy ; in Geniates bar- 
batus, another chafer in the male insect, the labium is 
naked, while the mentum, which forms a piece distinct 
from that part, is covered with a dense rigid beard ?. 
In shape the whole Jabium varies considerably, much 
more than the Jabrum ; for in addition to most of the 
forms I enumerated when I described that organ, which 
I shall not here repeat, you may meet with examples of 
many others. ‘Thus, to instance in the Petalocerous 
tribes (Scarabeus L.), in some, as in the Rutelida, the 
labium is urceolate, or representing in some degree the 
shape of a pitcher®; in others it is deeply concave, and 
not a little resembles a basin or a bowl*; this form is 
peculiar to the dabium of Cremastocheilus, a scarce North 
American genus; in another related to this, but of an 
African type (Genuchus cruentus), it is a trapezoid plate, 
which is elevated from the head, and hangs over the 
throat like a chin¢. In the Hymenoptera it is extremely 
narrow and long, and embraces the sides of the tongue, 
as well as covering it from below; so that it wears the 
appearance of a kind of tube *. Generally speaking, the 
length of the Jabium exceeds its breadth; but in the Pre- 
daceous beetles the reverse of this takes place, it being 
very short and wide, and usually terminating towards 
® Kirby Linn. Trans. xii. t. xxi. f. 8. f. 
> Ibid. ¢. xxi. f. 10. d. Macleay Hor. Entomol. i. t. iii. f. 26, 27. 
¢ Prate XXVI. Fic. 35. 4 Ibid. Fic. 34, 
© Puare VII. Fie, 3. b’. 
