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Litera-significations-
Where not stated otherwise, the litera-significations are the same in
all the l’lates.
mu. — Mouth.
an. — Cloacal aperture.
S.o. — Segmental glandulous sacks.
£ — Male genital aperture (Penis).
it. — Sub-ectodermal testes.
tn. — Tentacular nerves.
t.r — Tentacular nerve-ring.
cm\ cm", cm"’ — Nerves connecting the
tentacular nerve-ring with the oesophageal ring.
or. — Oesophageal ring.
O.cni. — Oesophageal commissures.
0.n. — Oesophageal nerves.
1.cm. —- Longitudinal commissures.
i.n. — Intermediate nerve.
n. — Nerves.
n.St. — Large nerves.
n.c. — Ganglionic cells.
gr. — Groups of ganglionic cells.
b.s. — Ventral nerve-cord.
f.<j. — l’arapodial ganglia.
n.sk. — Neurilemma-sheath.
ov.d. — Oviducts.
t. — Testes.
tm. — Intestinal branches.
ei. — Cloacal canal.
mv. — Stomach.
m. — Muscles.
h. — Hooks.
r.h. — Reserve hooks.
lik. — Hook-glands.
Figures.
Fig. I, 2. M. graffi, n. sp. Dorsal and ventral aspects; magnified about 15 times. (Cam.-luc.)
3. M. giganteum, n. sp. Magnified about 10 times. (Cam.-luc.)
4. Do. Anterior portion, dorsal aspect, proboscis extended; magnified 15 times. (Cam.-luc.)
5. M. gigas, Liitken. Complemental male. Ventral aspect; magnified 15 times. (Cam.-luc.)
» 6, 7. 31. carpenteri, Graff. Dorsal and ventral aspects; magnified 71/2 times. (Cam.-luc. and reduced to half size.)
8. M. giganteum, n. sp. (Zeiss AA. Oc. 1. Osmic acid. Hæmatoxylin1).) Ideal horizontal section through left-hand half,
representing the distribution of the nervous system. The illustration is obtained by means of a series of horizontal sections,
and is, partly, drawn under the Camera-lucida. At the base of the proboscis, the transsected oesophageal ring (or.), with
circumjacent groups of cells (gr.), is seen. At the anterior end of the muscular bulb, the transsected tentacular
nerve-ring (tr.), with the pertaining tentacular nerves (tn.), oesophageal nerves etc. and nerves (cm.) connecting it
with the oesophageal ring, is seen. In the centre of the section, the ventral nerve-cord, with its two
longitudinal commissures (l.cm.), between which ganglionic cells and the intermediate nerve are situated, is seen. 11 pairs
of nerves are seen to issue — 6 pairs of fine ones («.’—n.6) and 5 pairs of large ones — from the latter, branches run to the
parapodia and their muscles, also to the parapodial ganglia (/.♂.) and to some muscles in the body (e.), and to
the cirri and margin of the bod)-. At each cirrus, the branches form a complex ramification (a.) sending a bundle
of nerves into the cirrus, f. Branchlet of the medial nerve-branch, anastomozing with a branchlet from the ulterior posterior
nerve-branch. d. Parapodial nerve-branch dividing into two branchlets, the posterior one of which is the largest
and corresponds to the anterior branch at the three first pairs of parapodia. On the inner side of the hooks and their
surrounding muscles at each parapodium, the inner branch (h. k.) of the hook-glands is seen transsected. ß
Transsected depression in the ventrum at the outer side of each parapodium. Ovd. A latero-ventral oviduct opening into
the cloacal canal (ei.). Ovd. (at the lower margin of the figure) Transsected dorsal oviduct, et, et., et.
Sub-ectodermal testes, principally situated in the margin of the body.
» 9. Schematic representation of the structure of the oesophageal ring and proboscideal nervous system in
M. giganteum, 11. sp. Dorsal aspect. The anterior part of the ventral nerve-cord is seen, from which the oesophageal
commissures (o.cm.) forming the oesophageal ring issue; a few ganglionic cells occur in two places, one on each side
(a.) within its neurilemma-sheath. The mesial part (&.), on the dorsal side of the ring, is very thin and flat. The
ganglionic cells occurring between the oesophageal ring and the tentacular [nerve-ring are, to avoid confusion, not
illustrated in the figure, gr. Groups of cells, situated at the back of the oesophageal ring on the dorsal side, s.c"
The ventral portion of the cellular ring surrounding the proboscis. ri’. A nerve, proceeding towards the ventral side of
the proboscis, n. A nerve directed forwards, cm.’, cm ", cm.’". The three nerves connecting the oesophageal-ring
with the tentacular nerve-ring (t.r.) o.n. One of the 4 oesophageal nerves.2) n.s. Nervus sympathicus. n.st., n.st.2.
Respectively, the first and second of the large nerves issuing from the ventral cord, n’., ri’. Respectively, the first
and second of the fine nerves, Ganglionic cells are seen situated in the ventral cord, between the roots of the
nerves, as well as (c.) between the longitudinal commissures (l.cm.) and the intermediate nerve (in.).
10. Schematic representation of the tentacular nerve-ring viewed from the anterior side, o.n., o.n. and the two
corresponding nerves of the other side, are the roots of the 4 oesophageal nerves, cm., cm. are the roots of the
nerves connecting the oesophageal ring, n., n. Fine nerves passing to the walls of the proboscideal canal.
» 11. M. graffi, n. sp. (Zeiss AA. Oc. 1. Cam.-luc.) Transverse section through the posterior part of the body, at the
point where the lateral oviducts (ov.d.), issue from the dorsal oviduct (ov.d’). The lateral oviducts are, owing to
their meandering course, transsected 111 several places, n’, n’ The posteriorly directed 5th pair of large nerves.
n., n. The posterior 6th pair of fine nerves a. A small portion of the body cavity, in which ova are situated.
tm. A transsected dorsal branch of the intestine.
Where, in the description of the figures, »osmic acid, hæmatoxylin« is stated the specimens, preserved in alcohol, were immersed for 6 to
12 hours in a solution of i °/0 osmic acid, then washed out, stained with hæmatoxylin and imbedded. The sections were usually treated with a weak
solution of eosin in a mixture of turpentine and a little abs. alcohol. Where »Borax-carmine, picric acid ’ is stated the specimens were stained in toto with
borax-carmine; and the sections were treated with a solution of picric acid in a mixture of turpentine and abs. alcohol.
2) I am not certain that these nerves are connected with the oesophageal ring as indicated at d.
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