EXTERNAL ANATOMY OF INSECTS. 4.38 
dible?.. Many insects, however, have mandibles without 
teeth ; some merely tapering to a sharp point, others ob- 
tuse at the end, and others truncated®. Of those that 
have teeth, some have them on the inside at the base, as 
Manticora, an African tiger-beetle*; others in the mid- 
dle, as Goerius olens, a rove-beetle, Lethrus cephalotes, 
&c.4; others at the end, as many weevils (Rhyncophora)® ; 
others again on the back, as the Ruelide, a tribe of 
chafers‘, and Lethrus, a beetle just named; others once 
more on the lower side of the base, in the form of a 
tooth or spine, as in Andrena spinigera, a species of 
wild-bee, and some of its affinities’ ; and lastly, others 
on the upper-side of the base in the form of a long tor- 
tuous horn, as in that singular wasp Synagris cornuta, 
before noticed as a sexual character®. In the stag- 
beetle tribes (Zucanus) these teeth are often elongated 
into short lateral branches, or a terminal fork'. They 
are sometimes truncated, sometimes obtuse, and some- 
times acute. 
But with regard to their kind, it will be best to adopt 
the ideas of Marcel de Serres; for though his remarks 
are confined to the Orthoptera, they may be applied 
with advantage to the teeth that arm the mandibles of 
insects in general. He perceives an analogy between 
those of this Order and the teeth of quadrupeds; and 
* Marcel de Serres ubi supra, 7. 
» See Prarr XIE. Fic. 7. Kirby Mon. Ap. Angl. i. t. xiii. f. 15. 
and ¢. xii. neut. f. 10. r 
© Prate XXVI. Fie. 19. 
* Oliv. Zns. no. 42. t. i. f. I. and no. 2. t. i. f. 1. b. 
¢ Prats XXVI. Fic. 16, 18. f Ibid. Fig. 21. 
& Mon. Ap. Angl. i. t. iv. Melitta. f. 5—8. 
" Drury Ins. ii, ¢. xlviii. f. 3. See above, p. 314. 
i Oliv. no. lt. v. f. 16. &c. #. iii. f. 7. 
VOL, Ill. 2F 
