14? INTERNAL ANATOMY OF INSECTS, 
well as the brain, consist of two lobes : they are, however, 
seldom all precisely of the same shape. In the Dytisci, 
and Carabi, the last is marked with a transverse furrow, 
which seems to indicate the reunion of two a ; in the stag- 
beetle, the first ganglion is oval or elliptical, the second 
hexagonal ; the third and fourth shaped like a crescent, 
and the last like an olive b ; in the caterpillar of the great 
goat-moth the first is oblong and constricted in the mid- 
dle, and the seven last are rhomboidal c ; in the great 
Hydrophilus the second, and in the silk- worm all the gan- 
glions are quadrangular d ; in Hypogymna dispar the 
third is heart-shaped e ; the great ganglion which forms 
the spinal marrow of the cheese-maggot is pear-shaped f ; 
that of the grub of the rhinoceros-beetle is fusiform * ; 
and in the scorpion all the ganglions are lenticular h . 
But the most remarkable in this respect are those of a 
spider (Clubiona atrox) : in this insect the brain sits upon 
abilobed ganglion of the ordinary form, which is imme- 
diately followed without any internode by another bi- 
lobed one, terminating on each side in four pear-shaped 
processes or fingers, which give it a very singular ap- 
pearance '. 
iii. The nerves k of insects, as of other animals, are 
white filaments running from the brain and spinal mar- 
row to every part of the body which they are destined to 
animate ; and their numerous ramifications, when de- 
a Cuv. ubisupr. 339. b Ibid. 335—. 
c Lyonet Anat. 1 90. 
d Cuv. ubisupr. ii. 340. Malpigh. de Bombyc. t. xi.f. 2. 
e Cuv. Ibid. 348. * Swamm. Bihl. Nat. t. xlviii./. 7- 
* Cuv. Ibid. 319. h N. Did. d'Hist. Nat. xxx. 420. 
' Treviran, Arachnid, t. v./.45.m. 
* Plate XXI. Fig. 1.7.8. rf. 
