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35
er Hudens Struktur og de i den indleirede Hjul
fuldkommen lig dem hos Myriotrochus lyrevis. Kalkringen,
Vandkarringen og Stenkanalen afvige heller ikke. Sars omtaler
vel. at Stehkanalen er stilket og uden Kalk; men dette
stemmer ikke overens med vore Iagttagelser. Vi fandt, at
Stenkanalen hos Oligotrochus ritreus var aldeles lig den hos
Myriotroehus brevis, og da vi kort iforveien have beskrevet
denne, kunüe vi henvise dertil. Nervesystemet hos
Oligotrochus ritreus frembyder heller ingen Afvigelse fra
Myi’io-trochus brevis. Radialnerverne ere forsynede med to
saakaldte Høreblærer uden Otolither.- hvilke. sidde paa hver
Side af Radialstammen, strax bagenfor dennes Udspring af
Nerveringen.
Af det her anførte vil det formentlig erfares, at
Oligotrochus ritreus er identisk med Myriotrochus (Chirodota)
brems, og det tør derfor erkjendes, at der for os har været
fuld Grund til at opføre den i Synonymernes Række.
breris agree in the structure of the skin and the
wheel-shaped spicules embedded therein. Nor could we detect any
difference in the calcareous ring, the water vascular ring
and the sand-canal. True, the sand-canal, according to Sars. ’
is pedunculate and without calcareous deposit; but this
we did not find to be the case in the specimen examined.
The sand-canal in. Oligotrochus ritreus — we refer .to
our description of that organ — was exactly similar to
that in Myriotrochus breris; nor does the nervous system
in the one exhibit any difference whatever from that in the
other. The radial nerves are furnished with two auditory
vesicles, as they are called, without Otoliths, one on either
side of the radial stem, immediately posterior to its origin
on the nervous ring.
From what has here been stated, it will, we cannot
but think, be sufficiently clear, that Oligotrochus ritreus is
identical with Myriotrochus (Chirodota) brevis, and must,
therefore, be added to the list of synonyms.
Acanthotrochu81 mirabilis, n. g., n. sp.
Tab. V—VI. Fig. « og
Legemet er 10—12mm langt, cylindrisk, langstrakt;
bredere og afrundet i den bagre Ende. noget smalere i den
forreste og indkneben paa ilidteu. Huden fuldstændig
glasklar, og i den sees yderst fine gl indsende Punkter, der
under Loupen viser sig at være Kalkhjul. 5
Længdemuskler. 12 fingerformige Tentakler.
Huden.
Indenfor den strukturløse Cuticula er Epithélet. der
bestaar af et enkelt Lag Cylinderceller. Tab. V. Fig. 9. a,
hvilket fæster sig til et bredere hyalint Bindevæv. Fig. 9, b,
hvori sees hist og her enkelte Bindevævslegemer. .der dels
ere aflange, dels forsynede med en eller to Udløbere, Fig.
9, c, c; desforuden iagttages i det indre Lag. nærmest
Muskelhuden, flere isolerede ovale, temmelig klare Celler,
indeholdende Molekiiler (Semper’s Slimceller), Fig. 9. d.
Der. hvor Epithelet støder til Læderhuden, findes en fiel
Del enkelte pæreformige Legemer, hvis bredere, afrundede
Del er ligesom nedsænket i Corium, medens den smalere,
stilkede, forlænger sig op imellem Epitlielcellerne. Fig. 9,
e, e. Disse’ Legemer. Uer ere 0.006m" lange og 0.003""
brede, bestaa af en tynd gjennemsigtig Membran, der
Acanthotrochu8’ mirabilis, n. g., n. sp.
Pl. V—VI; fips. 8 and k’.
Body, measuring lo—12"" in length, cylindric. elon- •
gate, the posterior extremity rounded and somewhat broader
than the anterior; constricted in the middle. Skin
crystalline, its surface dotted with minute lustrous points, which,
examined under a lens, are found to be wheel-shaped
spicules of characteristic form. Longitudinal muscles 5.
Twelve digitated tentacula.
Skin.
Beneath the structureless cuticle extends the
epithelium, consisting of a single layer of cylindric cells, Pl. V.
fig. 9, a. webbed to a broad hyaline stratum, fig. 9, b,
in which are seen here and there a few cçrpuscles of
connective tissue, some of them oblong, some fyrnished
with one or two offshoots, fig. 9, c, c; moreover, in
the inner layer, next to the muscular integument, occur
several isolated, oval, semi-translucent cells, containing
molecules (Semper’s mucous cells), fig. 9. d. Between the
epithelium and the coriaceous integument are numerous
isolated pvriform corpuscles, having their broader rounded
part as it were embedded in the corium, the narrower,
pedunculate portion protending upwards between the
epithelial cells, fig. 9, e, e. These corpuscles, which measure
(xxaVsa — .en Pig og rpoyoc = et Hjul. ’ axavSa, a spike; rpoyoç, a wheel.
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