The visceral ganglion of Pecten, etc. 
39 
os' = osphradial nerve fibres from branchial nerve {Pecten fig. 1). 
os" = osphradial nerve fibres from osphradio-branchial nerve {Pecten fig. 1). 
os'" = osphradial nerve fibres from posterior nerve {Pecten fig. 1). 
os.h.n = osphradio-branchial nerve. 
os.p = posterior osphradial nerve. 
p.pall = posterior palÜal nerves. 
pall.n = palliai nerves. 
Pg 7= Pigment granules. 
fXl = right lateral lobe. 
s = area of so-called "spongiöse" substance. 
tr.f = transverse tract of nerve fibres in visceral ganglion of Pecten. 
v. c.l = ventro-central lobe. , 
vi. n = nerve from accessory ganglion to viscera. 
X = collecting path of nerve fibrillae from "spongiöse" substance. 
Piate 1. 
Fig. 1. Visceral ganglion of Pecten maximus seen from the ventral surface, the right 
side of the ganglion is on the left in the figure. The muscle nerves which lie 
below the palliai nerves are not shown. xl5. 
Fig. 2. Dorsal surface of visceral ganglion of Pecten maximus, the nerves are indicateci 
semidiagrammatically in this figure, x 10. 
Fig. 3. Vertical section through the left lateral lobe of Pecten jacolaeus, illustrating 
the origin of sensory fibres in the lateral lobes. x 90. 
Fig. 4.1) Section through visceral ganglion of Pecten jacobaeus, showing left lateral lobe 
and the areas of so-called "spongiöse Substanz". The branchial nerve is also 
indicated. x 90. 
Fig. 5. Section through visceral ganglion of Pecten jacóbaeus, showing the tract of nerve 
fibres {tr.-j) which runs across in the neuropil and branches near the lateral 
lobes. X 23. 
Fig. 6. Section through the visceral ganglion of Pecten jacóbaeus showing the palliai 
nerves arising from the left lateral lobe, x 10. 
Fig. 7, Section through the visceral gangUon of Pecten maximus illustrating the os- 
phradial nerves. x 12. 
Fig. 8. Section through the visceral gangÜon of Pecten maximus showing accessory 
ganghon and origin of osphradio-branchial nerve. x 10. 
Fig. 9. Pecten maximus emitting spermatozoa. 
Fig. 10. Ganghon celi from dorso-central lobe of P. maximus showing neurofibril net. 
Stained toluidin blue, x 750. 
Hg. 11. Ganghon celi from dorso-central lobe of P. maximus. Stained Iron Haema- 
toxylin. X 750. 
Fig. 12. Unipolar ganglion celi in maceration preparation of visceral ganghon of P. 
maximus. (Maceration in 1/3 alcohol). x 300. 
1) The photomicrographs figs. 4 — 8 are of sections taken in the same piane 
(that of the ganglion), but at different levels. 
