—_—— 
Se ees ss ae ae ee 
ELEDONE. 5A5 
ihe auditory nerve arise from the cerebral ganglion 
(Pelseneer). 
B. (10) There are eight Brachial Nerves given oft 
from the anterior edge of the brachial ganglion (fig. 70, 
Br. N.) which run forwards over the buccal mass, towards 
the bases of the arms. ‘They run on the outer side of 
the wall of the sinus venosus and may be seen there as 
broad flat bands. Between the above wall and these 
brachial nerves lie the labial nerves, dorsally. Each 
brachial nerve runs up the centre of an arm, internal to 
the corresponding brachial artery, and lessening towards 
the tip of the tapering arm (PI. IX, fig. 69, and Pl. VIII, 
fig. 80, Br. V.). At the base of the arms, in the region 
where they are joined on to the cephalic mass, a circular 
nerve cord joins the eight brachial nerves together 
(figs. 69 and 80, V.Czre.). This cord is of very peculiar 
structure. Between the nerves it is single, but in the 
region of the nerves it splits into two cords, of which the 
anterior joins on to the brachial nerve, while the posterior 
runs below it (fig. 69). Running up the arm the brachial 
nerve bears a series of long elliptical ganglia on its oral 
surface (Pl. IX, fig. 77, S.G.). Hach ganglion corresponds 
to a sucker, and gives off two rows of small nerves which 
run up to innervate these structures (fig. 77, S. V.) and 
also the muscles of the arm. A gelatinous transparent 
tissue fills the space between the nerve cord and the walls 
of the cavity containing it. 
B. (11) Interbrachial Nerves.—Several small nerves 
given off between the ventralmost brachial nerve and the 
one above this run out and innervate the bases of the 
arms. Also between the second and third, and the third 
and fourth brachial nerve, counting upwards from below, 
a fine nerve runs out to these muscles (fig. 70, J.6r.). 
B. (12) Nerves of the Head.—Just above the dorsal- 
