Description of a Species of Caligus. 251 
farther beyond the brain, than the brain beyond it in front. This 
ganglion gives off seven pairs of nerves in front and laterally, and 
two pairs behind, besides a central nerve or the spinal cord. 
The first two pairs originate at the centre of the anterior mar- 
gin, (d, e, fig. 20.) The inner is quite slender and appears to en- 
ter the mouth each side of the esophagus. The second has twice 
the diameter of the first ; it curves more outward, and is supposed 
to go to the mandibles and their muscles, These nerves pass under 
the buccal mass, and cannot be traced while it is in its natural po- 
sition. ‘They invariably appear broken off when the buccal mass 
is removed; and sometimes after detaching it, a nerve equal in 
size to the first, has been seen entering the mouth near the esoph- 
agus, as above stated. ‘These facts have been deemed sufficient 
to authorize the above opinion respecting the destination of these 
nerves. 
The third pair (f, fig. 20) arise from the anterior angle of the 
ganglion. ‘They give out a branch exteriorly to the muscles of 
the first pair of legs, and afterwards continue to these organs, and 
pass into the terminal joints after giving a branch to the basal. 
The fourth pair (g) arise just posterior to the last, and are dis- 
tributed to the outer teguments. They afford a branch near their 
origin, which probably passes to the rudimentary legs: soon after 
they divide into two parts; one branch passes outward anda 
little forward towards the curved spine, and subdivides into four 
branches before reaching it, which are distributed to the neigh- 
boring teguments; the other branch, extends backward to the 
epimeral articulation, just below the articulating processes, where 
it passes to the epimeral segment; it then branches, and is dis- 
tributed to the various parts of the inferior portion of this segment. 
The fifth pair (h) arise from the lateral margin of the gan- 
glion, some distance behind the preceding. They give off aslen- 
der branch near their origin, and pass along with the branch to 
the third pair of maxillipeds. 
-'The sixth pair (i) arise near the preceding, and are large nerves. 
They divide immediately, and then subdivide into several branch- 
es, which are distributed to the fourth pair of maxillipeds, and 
. The seventh pair (x) originate near the last, soon divide into 
two branches, which pass to the muscles of the same legs. They 
are slender nerves. 
