INTERNAL ANATOMY OF INSECTS. 15 



lineated, form no unpleasing picture a . In the caterpillar 

 of the goat-moth the accurate Lyonet counted forty- 

 Jive pairs of them, and two single ones, making in all 

 ninety-two nerves ; whereas in the human body anatomists 

 count only seventy- eight b . From the brain issue several 

 pairs, which go to the eyes, antennce^ palpi, and other 

 parts of the mouth : sometimes those that render to the 

 mandibles issue from the first ganglion, as in the larva 

 of Dytiscics marginalis, the stag-beetle, &c. c ; those both 

 of mandibles and palpi in the great Hydrophilus d ; and 

 in Elatta some which act also upon the antenna e . 



The optic are usually the most conspicuous and re- 

 markable of the nerves. In some insects with large eyes, 

 as many Neuroptera, Hymenoptera, and Diptera, their 

 size is considerable ; in the hive-bee they present the ap- 

 pearance of a pair of kidney-shaped lobes, larger than 

 the brain f ; in the dragon-flies, whose brain consists of 

 two very minute lobes, these nerves dilate into two large 

 plates of a similar shape, which line all the inner surface 

 of the eyes s in the stag-beetle they are pear-shaped, and 

 terminate in a bulb, from which issue an infinity of mi- 

 nute nerves h ; it is probable that this takes place in all 

 cases, and that a separate nerve renders to every separate 

 lens in a compound eye ' ; the optic nerve in Dytiscus and 

 Carabus is pyramidal, with the base of the pyramid at the 

 eye and the summit at the brain k ; in Eristalis tenax it 



Lyonet ubi supr. t. x./. 5. 6. b Ibid. 192. 



Cuv. ubi supr. 323. 335. 



Ibid. ii. 339. e md m 342. 



Swamm. Bill. Nat. t. xxii./. 6. m.m. 



Cuv. ubi supr. 350. h Ibid. 335. 



4 VOL. III. p. 495. Lyonet. Anat.5Sl. 

 k Cuv, ubi supr. 337. 



