STATES OF INSECTS. 121 



ber a . M. Cavier has observed, with regard to the man- 

 dibular of those of stag-beetles (Lucanus), that besides 

 their teeth at the extremity, they have towards their base 

 a flat striated molary surface ; so that they both cut and 

 grind their ligneous food b . It seems to have escaped 

 him, that a similar structure takes place in many perfect 

 insects of the lamellicorn tribe, as I shall hereafter show 

 you. In the larvae of the water-beetles (Dytiscus L.), 

 ant-lions (Myrmeleon L.), and lace-winged flies (Hemero- 

 bins L.), they resemble somewhat the forceps at the tail 

 of an ear-wig, being long and incurved ; and, what is more 

 remarkable, hollow and perforated at the end, so as to 

 serve as a channel for conveying into the larva's mouth 

 the juices of the prey which by their aid it has seized. 

 Reaumur even asserts, that the larva of Myrmeleon has 

 no other entrance into its throat than through these tu- 

 bular mandibles c . That of the rove-beetles (Slap/iy- 

 linus L.), and of many other Coleopterous genera, have 

 these organs of this forcipate construction, without being 

 perforated" 1 . In the larva of the carnivorous flies, and 

 many other Diptera, are two black incurved subulate 

 parts, connected at the base, and capable of being pro- 

 truded out of, and retracted into, the head, through the 

 skin of which they are usually visible. As I informed 

 you in a former letter e , these mandibles are used for 

 walking as well as feeding : they are parallel to each 

 other, and are neither formed for cutting nor grinding 



a Kirby in Linn. Trans, v. t. xii./.7 b. 

 b Cuvier Anat. Covip. hi. 322. c Reaum.Vi. 340. 



d The larva of Cicihdela campestris has mandibles of this descrip- 

 tion. Plate XVII. Fir,. 13. c c. 

 e See above, Vol. II. 275 — . 



