82 THE ARACHNOIDAE. $ 801. 
The ventral chain of the Pycnogonidae. is composed likewise of four 
ganglia, but these, which send off, each, a nerve from its side to the corre- 
sponding foot, are contiguous, and the first connects with the ovoid cerebrab 
ganglion by two lateral commissures. 
With the Araneae, the central portion of the nervous system consists of 
a large sub-cesophageal ganglion, and another, smaller and above the cesoph- 
agus. They are separated from each other only by a narrow fissure 
through which the oesophagus passes. The super-cesophageal ganglion, 
which is somewhat emarginated in front, corresponds to the brain, and 
sends off nerves to the eyes and cheliceres. The sub-cesophageal gan- 
glion, situated in the middle of the cephalothorax, sends off, on each side,. 
four larger processes, from which arise the nerves of the feet. Its anterior 
border supplies, moreover, the nerves of the two palpi; and from its poste- 
rior margin pass off two nerves for the abdominal viscera. © 
The nervous system of Galeodes,” Phrynus, and Thelyphonus,” has a 
like disposition. 
The central mass of the nervous system of the Phalangidae begins by 
two conical, contiguous cerebral ganglia, which connect with.a sub- 
cesophageal, fused ganglion, by two short lateral commissures. This ven- 
tral ganglion is composed of a transverse portion, which is situated in the 
centre of the cephalothorax, and of two lateral portions which consist, each, 
of an anterior or larger, and a posterior or smaller lobe. These. lobes send 
off nerves to the eight legs, and in front, others to the palpi; while from 
the posterior border of the transverse portion pass off several nerves to the 
viscera of the abdomen. ® 
With the Scorpionidae, the nervous system is very highly developed. 
The brain, which is: not large, is composed of two spheroidal, super- 
cesophageal ganglia fused together. Above, and in front, they send off 
nerves to the eyes and the cheliceres; and below, they connect with the 
first ventral ganglion by two short, large filaments, which embrace the 
cesophagus. The first ;ventral ganglion is pretty large, being the result, 
probably, of the fusion of several ganglia. It is situated in the middle of 
the cephalothorax, and sends nerves to the palpi and to the eight legs. In 
the rest of the body there are three ventral ganglia, smaller, and followed 
by four others situated in the tail. All these ganglia are connected by 
double, longitudinal commissures, and the posterior seven give off, from 
each side, two nerves; while from the last ganglion arise also two others, 
which, passing backwards, soon unite and extend to the very extremity of 
the tail, sending off nerves right and left. 
4 Quatrefages, loc. cit., 77, Pl. I. fig. 1* 24; also 
Pl. IL. fig. 2, 3 (Ammothea and Phoxichilus). 
5 Treviranus, Ueber d. inn, Bau d. Arach. p. 
4A, Taf. V. fig. 45, and Zeitsch. f. Physiol. IV. p. 94, 
Taf. VI. fig. 4; Lyonet, loc. cit. p. 405, Pl. XXI. 
fig. 22; Brandt, Mediz. Zool. II. p. 90, Taf. XV. 
fig. 3, 4, or Ann. d. Sc. Nat. XIII. p. 184, Pl. IV. 
fig. 4. Duges, Ibid. VI. p. 174; Grube, loc. cit. 
p. 302, and finally Owen, Lectures, &c., p. 255, fig. 
109. This last author has represented, in a very. 
instructive manner, the nervous system of a Mygale 
seen in profile. 
6 Blanchard, loc. cit. p. 1384. 
7 Van der Hoeven, Tijdschrift. loc. cit. IX. 
1842, p. 68, and X. 1843, p. 369. 
*[§ 301, note 9.] See also Dufour (Ann d. 
Sc. Nat. XV. 1851, p. 250). This anatomist has 
found a fourth abdominal ganglion, d just 
8 The nervous system had already been partially 
described by T'reviranus (Verm. Schrift. I. p. 38, 
Taf. IV. fig. 24) ; but especially, and with full de- 
tails, by 7'ulk, loc. cit. p. 324, Pl. V. fig. 31. 
9 For the nervous system of the Scorpionidae, 
see Treviranus (Bau. d. Arach. p. 14, Taf. I. fig. 
18, and Zeitschrift f. Physiol. IV. p. 89, Taf. VI. 
fig. 1-3, and Muller, loc. cit. p. 60, Taf. I. fig. 5, 
7); but especially Newport’s excellent description 
(Philos, Trans. 1843, p. 260, Pl. XII.); he has 
traced, with Androctonus, the nerves of the ex- 
tremities even into the tarsal articles and terminal 
hooks.* a 
behind the thoracic mass, from which passes 
off a pair of nerves to the pulmonary organs 
(Scorpio occitanus). — Ep, 
