SPECIAL ANATOMY. 241 
while in Vaginulus it is so short that the two sets of gan- 
glia form a close ring around the anterior part of the 
buccal body. 
The third set of ganglia are the stomato-gastric, con- 
sisting of two minute, lateral masses, united by a short, 
transverse commissure, and always placed upon the buc- 
cal body immediately postero-laterally to the commence- 
ment of the oesophagus. The stomato-gastric ganglia are 
connected with the supra-oesophageal on each side, by 
means of a long, delicate commissure, which is more or 
less loose, and permits a free movement of the former 
ganglia with the buccal body to which they are fixed. 
From the supra-oesophageal ganglia pass off on each 
side, — 1st, a minute branch along the course of the 
supra-sub-oesophageal commissure ; 2d, three or four small 
branches to the retractor muscles of the tentaculse ; 3d, 
a large branch, the superior tentacular nerve ; 4th, one 
or two small branches to the base of the superior tenta- 
cle, for its integument ; 5th, the inferior tentacular 
nerve ; 6th, small branches to the integument of the 
lips. 
From the sub-oesophageal ganglia pass off, — 1st, nume- 
rous branches on each side, to the podal disk, and late- 
rally to the integument ; 2d, a branch on the right side 
to the penis ; 3d, a branch to the vas deferens and pros- 
tate gland ; 4th, on each side a branch to the retractor 
muscle of the buccal body ; 5th, a large one to each side 
of the collar and pulmonary chamber ; 6th, a branch 
which follows the posterior aortic vessel, which gives off 
von. i. 62 
