8 INTERNAL ANATOMY OF INSECTS. 
cervical ganglion, which Dr. Virey regards as its ana- 
logue*—is certainly to be found in them; and as Messrs. 
Cuvier and Lamarck distinguish this part by the name 
of brain, we may continue to call it by that name with- 
out impropriety. The drain of insects, then, is distin- 
guished from the succeeding ganglions of the spinal chord 
by its situation in the head, the middle of the internal 
cavity of which it occupies, and by being the only gan- 
glion above the cesophagus. It is usually small, though 
in some cases larger than they are’. It consists of two 
lobes, more or less distinct and generally of a spherical 
form. In Oryctes nasicornis and Pieris Brassice the 
lobes are separated both before and behind * ; while in the 
larvaof Dytiscus marginalis, but not in the imago, in which 
there are two large hemispheres separated by a furrow, 
the brain is undivided¢. Cuvier mentions the larva of 
a Tenthredo L. in which this part is formed of four nearly 
equal spherical bulbs*: in the Scorpion (to judge by the 
figure of ‘Treviranus*) the two lobes represent an equi- 
lateral triangle, the exterior angle of which terminates 
in several lesser spherical bulbs; in Acrida viridissima, 
Nepa cinerea, Clubiona atrox, and the common Louse, the 
lobes are pear-shaped &, 
ii. The spinal marrow and its ganglions*. From the 
posterior part of the brain of insects, but in Carabus and 
Dytiscus L. from its sides below’, issue two chords which 
. 
@ N. Dict. d Hist. Nat. xxii. 527. > Ibid. v. 591. 
© Cuv. Anat. Comp. ii. 318. Swamm. Bibl. Nat. t. xxix. f.7. He- 
rold Schmetterl. t. ii. f. 1—10. a. * Cuv. Ibid. 322. 337. 
€ Tbid. 324. * Arachnid. t.i. f. 13. m.m. 
© Cuv. whi supr. 343.346. Treviranus Arachnid. tiv. f. 45. a. 
Prats XXI. Fic. 8.4, Ibid. Fie. 1.8.5. i Cuyeudi supr. 337. 
