INNERVATION OF CERATA OF SOME NUDIBRANCHIATA. 547 
100 sections to one of the first pair of cerata, which it enters 
(in 231st section in this series), and is then distributed. 
Fig. 8 (Pl. XXXII) shows the main nerve (ep. ”.) in a com- 
partment of the body-cavity, the dorsal branch (d.) in the 
body-wall, and twigs from the latter (c.) passing up into the 
ceras above. In about the 240th section (see Pl. XXXII, 
fig. 9) the epipodial nerve, still in the body-cavity, gives off 
a small branch, which is distributed to the lateral body- 
wall. In the 258th section the branch to the second ceras 
arises. The epipodial nerve has now become more dorsal in 
position, and it soon leaves the body-cavity and sinks into the 
body-wall, where it gives off small branches to the dorsal in- 
tegument and to the branchiz. In about the 312th section 
the branch of the third ceras is given off, and the main nerve, 
now very small, runs back a little further, and then breaks up 
into the delicate twigs which supply the fourth and fifth pairs 
of cerata. 
In another small specimen of Ancula cristata we find the 
epipodial nerves arising from the dorsal surfaces of the pleural 
ganglia, just posterior to the cerebrals (see Pl. XXXII, fig. 7, 
ep. n.) on both sides in the 96th section. ‘The nerves then 
run back in the body-cavity to section 130, where they give 
off their first dorsal branches to the first pair of cerata. 
Some of the sections of Ancula show the histology of the 
ganglia well (see Pl. XXXII, figs. 5, 6,7). There is a con- 
nective tissue sheath, which becomes thicker where a nerve 
leaves, and is then continued along the nerve (see fig. 6, p. 7. 
and sh.). The large nerve-cells are distributed round the peri- 
phery of the ganglion, while the centre is occupied by small 
cells and interlacing delicate nerve-fibres. 
DENDRONOTUS. 
Bergh! states that in Dendronotus arborescens the 
cerata are supplied by nerves arising from the pleural ganglia ; 
but we find in addition an interesting anastomosis of a branch 
1 “Die Nudibran. d. ‘ Willem Barents,’”’ Bijdragen tot de Dierkunde, 
‘Nat. Artis Mag.,’ Amsterdam, 13° Afl,, 1886, p. 28, 
