14 INTERNAL ANATOMY OF INSECTS. 
glions are quadrangular*; in Hypogymna dispar the 
third is heart-shaped”; the great ganglion which forms 
the spinal marrow of the cheese-maggot is pear-shaped ¢ ; 
that of the grub of the rhinoceros-beetle is fusiform 4 ; 
and in the scorpion all the ganglions are lenticular °. 
But the most remarkable in this respect are those of a 
spider (Clubiona atrox): in this insect the brain sits upon 
a bilobed 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, 
ili. The nerves® of insects, as of other animals, are white 
filaments running from the brain and spinal marrow to 
every part of the body which they are destined to ani- 
mate; and their numerous ramifications, when delineated, 
form no unpleasing picture’. In the caterpillar of Cos- 
sus ligniperda the accurate Lyonnet counted forty-five 
pairs of them, and zwo single ones, making in all nznety- 
two nerves; whereas in the human body anatomists 
count only seventy-eight'. From the brain issue several 
pairs, which go to the eyes, antenne, palpi, and other 
parts of the mouth: sometimes those that render to the 
mandibles issue from the first ganglion, as in the larva 
of Dytiscus marginals, the stag-beetle, &c.*; those both 
* Cuv. Anat. Comp. ii. 340. Malpigh. de Bombyc. t. vi. f. 2. 
> Cuv. Jbid. 348. © Swamm. Bibl. Nat. t. xlviii. £. 7. 
4 Cuv. Ibid. 319. © N. Dict. d’ Hist. Nat. xxx. 420. 
 Treviran. Arachnid. t. v. f. 45. m. 
Pram OX. Nie. 17 Sad. 
n Lyonnet wi supr. t. x. f. 5. 6. ' Ibid. 192, 
K Cuv. ubi supr. 323. 335. 
