12 INTERNAL ANATOMY OF INSECTS. 
by numerous radiating nerves a ; in others again, as in 
the scorpion, they are all abdominal. The ganglions 
vary also in their situation with respect to each other. 
Thus in some, as in the larva of the Chamaileon-fly 
[Stratyomis Cham<rlcon\ they are so near as to appear 
like a string of beads b ; in that of the ant-lion (Myrme- 
Icon) the two ganglions of the trunk are separated by an 
interval from those of the abdomen, which are so conti- 
guous as to resemble the rattle of the rattle-snake c . In 
others the internodes are longer, and the ganglions occur 
at nearly equal intervals, as in the larva of the Ephe- 
mera* ; but in the majority they are unequal in length : 
thus in the scorpion the three first ganglions are the most 
distant c ; in the hive-bee the third and fourth f ; and in 
the spider the last g . 
2. The ganglions also in different species, and often 
in the same insect in its different states, vary in their 
number. Thus in the grub of the rhinoceros-beetle the 
whole spinal marrow appears like a single ganglion di- 
vided only by transverse furrows h ; in the water-scorpion 
there are tzvo ' ; in the louse there are three k ; in the rhi- 
noceros-beetle there axe four x ; five in the stag-beetle m ; 
a Plate XXI. Fig. 7- 
b Swamm. ubi supr. t. xl./. 5. Cuvier (ii. 33.2.) accuses Swam- 
merdam of representing the spinal marrow in this grub as producing 
nerves only on one side; whereas he expressly states (ii. 50. b.) that 
a considerable number spring on each side from the eleven ganglions, 
but that to avoid confusion he had omitted some. 
c Cuv. ubi supr. 325. d Swamm. Bill. Nat. t. xv.f. 6. 
Treviran. Arachnid, t. \.f. 13. 1 — 4. 
f Swamm. ubi supr. t. \\W.f. 7- 
E Treviran. ubi supr. /. v. /. 45. '' Plate XXI. Fig. 7. 
* Cuv. Anal. Comp. ii. 34G. k Plate XXI. Fig. 8. 
' Cuv. ubi supr. 337. ™ Ibid. 335— . 
