426 THOS. H. MONTGOMERY jr., 
nerve cells are evenly arranged along the whole nerve cord, and show 
no massing into particular ganglia; the nerve cord is not segmentally 
constricted; its neural lamella is a continuous, unbrdken sheet; the 
nerve fibres which pass into this lamella and from it into the hypo- 
dermis are arranged closely one behind the other, without being ar- 
ranged in particular bundles (nerves) or being regularly paired. There 
is no supra-oesophageal ganglion. The nerve cord is essentially an 
unpaired structure, and appears more distinctly tripartite than bi- 
partite. The bifurcation of the cephalic nerves at the anterior end 
represents simply the here separated fibrous tracts, and the bifurcation 
of the caudal nerves in the male probably does not represent a 
primitive paired condition of the central nervous system but has been 
secondarily produced by the ingrowth of the cloaca. The nervous 
system is rather a diffuse one, nerve cells being found along the 
hypodermis, especially dorsally, in the whole trunk region. 
Literature on the nervous system. VILLoT (1874) proved 
conclusively that the ventral cord represents the central nervous system 
of the Gordiacea, and described its anterior and posterior ganglion, 
and general anatomical structure. In 1887 he showed that nerves 
pass from the “ganglion c&phalique” into the thickened hypodermis 
of the head; concluded the hypodermis to be a peripheral nervous 
layer; and showed that in the female of Gordius presli the posterior 
end of the nerve cord bifurcates (this I have found to be the case 
also in Chordodes morgani MonTG.). In another paper (1889a) VILLOT 
retracts his opinion of the hypodermis representing a peripheral nervous 
layer, and states briefly (giving no figures) that the ganglion cells have 
two kinds of processes, in addition to their commissures; one kind, 
which penetrate the “perimysium” and innervate the muscle cells; 
another kind, which transverse the hypodermis and terminate in the 
cuticular papillae, which he considers to be organs of touch. 
VEJDOVSKY strongly disputes the existence of a peripheral nervous 
layer, in the form described by Vittor. He distinguishes two parts 
in the nervous system: the “Peripharyngealganglion”, and the “Bauch- 
strang” which posteriorly forms a “Schwanzganglion”. The peri- 
pharyngeal ganglion has only a single layer of ganglion cells on its 
upper side. The “Bauchstrang” consists of a lower ganglion-cell layer, 
and an upper “Nervenfaserschicht”, and the radial processes from the 
ganglion cells divide the fibrous mass into three parts; transverse 
commissures occurring at intervals are also described. The peripheral 
