SPECIAL ANATOMY. 245 
Within the tube of the retractor muscle of the tenta- 
culie, passes to the free extremity of the latter the ten- 
tacular nerve. When the tentaculse are retracted, the 
nerve becomes tortuous, and spiral, but when fully pro- 
truded it is nearly straight, or merely undulated. 
Near the free extremity of the superior tentaculse the 
nerve undergoes a sudden constriction, and then dilates 
into a gangliform enlargement, from the outer side of 
which proceeds a small division of the tentacular nerve, 
as the optic nerve, to the eye. The gangliform enlarge- 
ment is composed, on the exterior, of the nerve-tubuli of 
the tentacular nerve, and on the exterior, of a soft, white, 
finely granular matter, containing, in the exterior layer, 
round, granular, nuclear bodies. Anteriorly, the enlarge- 
ment undergoes a constriction, and then dilates into the 
large, bulbous mass of the extremity of the tentaculse. 
This latter mass is white, soft, and finely granular. 
Upon its exterior, the nerve-tubuli of the exterior of the 
first gangliform enlargement diverge, and divide into a 
number of large branches, which laterally subdivide into 
numerous smaller branches, and thus inclose the granu- 
lar mass. 
The inferior tentaculce present the same nervous struc- 
ture, except that there is no well-marked constriction 
between the tentacular nerve and the first gangliform 
enlargement, nor between the two enlargements, nor is 
there any optic nerve. 
The space between the tentacular nerve and the 
retractor muscle, is filled with a filamentous tissue, con- 
vol. i. 63 
