77 



the auditory nerve arise from (.lie 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 venosns 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 inns up the centre of an arm, internal to 

 the corresponding brachial artery, and lessening towards 

 the tip of the tapering arm (PI. IX, fig. (ii), and PI. VIII, 

 fig. <SU, Br. A.). 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, (if) and 80, N.Circ). 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. G9). Punning up the arm the brachial 

 nerve bears a series of long elliptical ganglia on its oral 

 surface (PI. IX, fig. 77, S.G.). Each ganglion corresponds 

 to a sucker, and gives off two rows of small nerves which 

 run up to innervate these structures (fig. 77, S. N.) and 

 also the muscles of the arm. A gelatinous transparent 

 tissue fills the space between the nerve cord and the Avails 

 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, I.br.). 



B. (12) Nerves of the Head — Inst above the dorsal- 



