372 THE ARACHNOIDAE. § 301. 



The ventral chain of the Pycnogonidae is composed likewise of four 

 ganglia, but these, which send oif, each, a nei've from its side to the corre- 

 sponding foot, are contiguous, and the first connects with the ovoid cerebral 

 ganglion by two lateral commissures.''" 



With the Araneae, the central portion of the nervous system consists of 

 a large sub-oesophageal ganglion, and another, smaller and above the oesoph- 

 agus. They are separated from each other only by a narrow fissure 

 through which the oesophagus passes. The super-oesophageal ganglion,, 

 which is somewhat emarginated in front, corresponds to the brain, and 

 sends off nerves to the eyes and cheliceres. The sub-oesophageal gan- 

 glion, situated in the middle of the cephalothorax, sends off, on each side,, 

 tour 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,^^'' Phrymis, 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- 

 oesophageal, fused ganglion, by two short lateral commissures. This ven- 

 tral ganglion is composed of a transverse portion, which is situated in the- 

 centi-e 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 

 ofi 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- 

 oesophageal ganglia fused together. Above, and in front, they send ofl^ 

 nerves to the eyes and the cheliceres ; and below, they connect with the- 

 first ventral ganglion by two short, large filaments, which embrace the 

 oesophagus. 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. lit 

 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 oft" nerves right and left.'''' 



4 Qiiatrefa^en, loc. cit., 77, PI. I. fig. l" 2>; also R The nervous system had already been partially 

 PI. H. tig. 2, S {Ammothea and Plwxickilus). described by Treviranu.s (Verm. Schrift. I. p. 38, 



5 TTe.viranux., Ueber d. inn. Bau d. Arach. p. Taf. IV. fig. 24) ; but especially, and with full de- 

 44, Taf. V. fig. 45, and Zeitsch. f. Physiol. IV. p. 94, tails, by Tulk, loc. cit. p. 324, PI. V. fig. 31. 



Taf. VI. fig. 4 ; Lyonet, loc. cit. p. 405, PI. XXI. 9 For the nervous system of the Scorpionidae, 

 fig. 22 ; Brandt, Mediz. Zool. H. p. 90, Taf. XV. see Treviranus (Bau. d. Arach. p. 14, Taf. I. fig. 

 fig. 3, 4, or Ann. d. Sc. Nat. XIII. p. 184, PI. IV. 13, and Zeitschrift f. Physiol. IV. p. 89, Taf. VI. 

 fig. 4 . DtiKiK, Ibid. VI. p. 174 ; Grube, loc. cit. fig. l-;j, and Müller, loc. cit. p. 60, Taf. I. fig. 5, 

 p. 302, and finally Oiven, Lectures, kc, p. 255, fig. 7) ; but especially Newport's excellent descriptiott 

 109. This last author has represented, in a very (Philos. Trans. 1843, p. 260, PI. XII.) ; he ha» 

 instructive manner, the nervous system of a JV/i/g-oie traced, with Androctonu.i, the nerves of the ex- 

 seen in profile. treinities even into the tarsal articles and t^irmiual 



G li/anckard, loc. cit. p. 1384. hooks.* 



7 yan der IJoei'en, Tijdschrift. loc. cit. IX. 

 1842, p. 68, and X. 1843, p. 369. 



* [ § 301, note 9.] See also Dufour (Ann d. behind the thoracic mass, from which passes 

 Sc. Nat. XV. 1851, p. 250). This anatomist has off a pair of nerves to the pulmonary organ» 

 found a fourth alxloininal ganglion, situated just (ßcorpio occitanas). — Ed. 



