334 THE DOLABELLINAE. 
Pedal nerves——Nine pairs of nerves arise from the lateral and posterior — 
margins of the pedal ganglia. They will be described in the order of their 
occurrence from before backward as numbered in Plate 2, fig. 1, and in Plate 5, — 
fig. 2, the origin and distribution being the same for both right and left sides, 
unless otherwise indicated. 
The first pedal nerve, /, arises as a strong trunk from the outer anterior 
portion of the superior face of the pedal ganglia. It passes directly forward — 
parallel to the bulbar aorta and gives off a slender external branch, Ja close ~ 
to its origin. This ramus is distributed mainly to the anterior region of the 
lateral retractor muscles of the head, a large branch also forming an anastomosis - 
with the second pedal nerve, 2, as shown in the figure. At about 9.0 mm. from — 
its origin the main trunk of the first nerve bifurcates, its two subdivisions each : 
dividing in turn almost at once. The four main branches thus formed are 
distributed to the most anterior portions of the foot. 
The second pedal nerve, 2, is strong, upon the left side being nearly as” 
large as the first. It arises from the antero-lateral face of the pedal ganglion, — 
just behind and external to the first nerve, and passes obliquely forward, receiv- 
ing the anastomosing branch of the first, just above the lateral retractor of the 
head. Passing between the fasciculi of this muscle to its outer face, it courses 
forward between it and the body-wall, giving off branches to the lateral rectractor 
and to the ventro-lateral body-wall at the margin of the foot. 
The third nerve, 3, is made up from the union of a number of delicate roots. ; 
Upon the left side three of these may be distinguished, the first arising close above — 
the origin of the second nerve, the second from the lateral face of the pedal 
ganglion, while the third is not a pedal nerve but arises from the left pleural 
ganglion (pl. 1). These unite in a common epineural sheath and are distributed | 
to the lateral body-wall in front of the eye. On the right side at least three 
delicate roots arise from the pedal ganglion, while a fourth springs from the 
right pleural ganglion and joins the first three in a common sheath. The first 
root appears to maintain its separate existence, the remaining three, or possibly 
four uniting in a common trunk a short distance from the ganglion. The group 
sends an anastomosing branch to the first cerebral nerve, and is distributed — 
to the lateral body-wall in front of the eye, and to the posterior retractor muscles 
of the penis-sheath. 
The fourth pedal nerve, 4, arises from the ventro-lateral surface of the 
pedal ganglion as a moderately strong trunk. It passes outward and forward 
below the lateral retractor muscle to the ventro-lateral body-wall, and curves 
