r9 
The cephalie ganglion is single, sitwated in front of the 
buccal mass and comparatively very small (0.3 by 0.3 mm.). 
Besides numerous nerve-branches to the different tissues of the 
head, three pair of principal stems separately originate from 
it (fig. 40). The innermost pair closely surround the muscular 
pharynx and form a nerve-ring. (sublingual commissure) in which 
a pair of sublingual ganglia occur just behind the tongue and 
radular sac (fig. 42, c, c). In the possession of this sublingual 
commissure Proneomenia fully corresponds with Chiton as results 
from a comparison with the diagrammatie sketch given by SPRNGEL 
(30) of the nervous centres of this genus, the sublingual ganglia 
in the latter being apparently contiguous, whereas in Proneomenia 
a commissure running round behind the radular sac unites them. 
That different nerves of various sizes originate from this ring and 
penetrate into different parts of the lingual apparatus is further 
illustrated by fig. 42. 
The second pair of prineipal nerves originating from the cerebral 
ganglion (fig. 40, cpe, pe), similarly surrounds the pharynx, but at a 
greater distance; somewhat behind the sublingual eommissure just 
noticed and close to the front end of the ventral furrow each of these 
nerve-stems dilates into a ganglionic swelling. These are the anterior 
pedal ganglia, connected by a commissure and giving rise to the parallel 
longitudinal pedal nerves '), which have the same situation as in 
Neomenia and are similarly united by transverse commissures (about 
0.65 mm. apart). The middle portion of these commissures (fig. 24) lies 
inside the ventral sinus, in the way v. GRAFF described it for Neomenia; 
they are present down to the posterior extremity of the pedal ner- 
ves. Here each of the latter dilates into another rather consider- 
I) In preference both to v. Ihering's and Spengel's nomenclature I 
propose to designate the longitudinal nerve-stems of the Amphineura by 
names that shall be as neutral as possible. The name pedal nerves can be 
retained for the inferior pair, for the superior (Spengel’s: visceral commis- 
sure, v. Ihering's »primary pallial”’, Brandt's »branchial” nerves), which 
serve towards the innervation of many different tissues, the name: lateral nerves, 
already used by v. Graff, should rather be chosen in these archaic forms. 
