14 INTERNAL ANAT#-M*OF INSECTS. 



? s 



well as the brain, consist of two lobes : they are, however, 

 seldom all precisely of the same shape. In the Dytisci, 

 and Carabi 9 the last is marked with a transverse furrow, 

 which seems to indicate the reunion of two * ; 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. 5 ; 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 g ; 

 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 

 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 '. 



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. 190. 



d Cuv. ubisupr. ii. 340. Malpigh. de Bombyc. t. \\.f. 2. 



8 Cuv. Ibid. 348. t Swamm. Bill. Nat. t. xlviii./. 7. 



Cuv. Ibid. 319. h N. Diet. tfHist. Nat. xxx. 420. 



' Treviran, Arachnid, t. \.f. 45. m. 



* PLATE XXK FIG. 1. 7. 8. d. 



