10 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
the anterior side. Of the two dorsal nerves, the more median and 
larger one runs to a ganglion-like mass on the side of the neck. This 
mass, which is of considerable size, sends nerve fibers to the surface 
as sho-RTi in figure 10 (pi. 3), where there may be a small sensory area. 
This nerve seems to be homologous with that in Clione described by 
Pelseneer ('87) as belonging to the posterior tentacle and by Boas ('86) 
as probably the olfactory nerve. In this case the slight elevation of 
the surface would be the representation of the nuchal tentacle. Lat- 
eral to this one is the other nerve arising from the dorsal side of the 
ganglion. This second nerve has a ganglionic swelling at its base. 
It runs parallel to the first and like it has an enlargement at its end (pi. 
3, fig. 9, oytg). This is evidently the homologue of the optic nerve of 
Clione, but I find nothing in connection with it that I can interpret as 
an eye. The distal enlargements of these two nerves lie side by side- 
and, as Boas pointed out for Clione, there is a connecting nerve near 
their proximal end. Unlike the condition in Clione, the two enlarge- 
ments are not at all equal in size, that of the more lateral ("optic") 
nerve being very much the smaller. 
Of the three nerves arising more anteriorly from each of the cerebral 
ganglia, the median (pi. 3, fig. 9, ce i) is a large trunk which divides 
immediately, sending one branch laterally and forward to supply the 
back of the head, and another inward to the esophagus and buccal 
mass. The middle nerve {ce 2) which is also large, supplies the tenta- 
cle of the corresponding side. The lateral nerve {ce 3), smaller than 
the two others, runs to the buccal mass. 
I find six nerves arising from each pedal ganglion. The two largest 
of these arise close together from the ventral side of the ganglion in 
front. The anterior one (pi. 3, fig. 9, jn) extends forward and sup- 
plies the foot, while the other (pn) enters the parapodium where it 
immediately distributes itself. Dorsal to these two is a somewhat 
smaller nerve {pd 1) that takes a general anterior direction. More 
posteriorly and below the otocyst {ot) there arises a very delicate 
nerve {pd4) and behind and below it a larger one {pdo). These two 
are probably the cervical nerves of Clione and other forms. The 
sixth nerve {pd 6) arises near the posterior side of the ganglion and 
very soon ana.stomoses with the nerve from the pleural ganglion. 
Pelseneer has shown that an anastomosis of these two nerves is com- 
mon to various pteropods. 
Each pleural ganglion gives rise to but a single nerve {pin) which^ 
