er Hudens Struktur og de i den indleirede Hjul fuldkom- 
men lig dem hos Myriotrochus brevis. Kalkringen, Vand- 
karringen og Stenkanalen afvige heller ikke. Sars omtaler 
vel, at Stenkanalen er stilket og uden Kalk: men dette 
stemmer ikke overens med vore Iagttagelser. Vi fandt, at 
Stenkanalen hos Oligotrochus vitreus var aldeles lig den hos 
Myriotrochus brevis, og da vi kort iforveien have beskrevet 
denne, kunne vi henvise dertil. Nervesystemet hos Oligo- 
trochus vitreus frembyder heller ingen Afvigelse fra Myrio- 
trochus brevis.  Radialnerverne ere forsynede med to saa- 
kaldte 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 Oli- 
gotrochus vitreus er identisk med Myriotrochus (Chirodota) 
brevis, og det tør derfor erkjendes, at der for os har været 
fuld Grund til at opføre den i Synonymernes Række. 
Acanthotrochus' mirabilis, n. g., n. sp. 
Tab. V—VI, Fig. 8 og 81 
Legemet er 10—12”” langt, eylindrisk, langstrakt, 
bredere og afrundet i den bagre Ende, noget smalere i den 
forreste og indkneben paa Midten. Huden fuldstændig 
glasklar, og i den sees yderst fine glindsende Punkter, der 
under Loupen viser sig at være Kalkhjul. 5 Længdemusk- 
ler. 12 fingerformige Tentakler. 
Huden. 
Indenfor den strukturløse Cuticula er Bpithelet, der 
bestaar af et enkelt Lag Cylinderceller, Tab. VY, 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 Slimeeller), Fig. 9, d. 
Der, hvor Epithelet støder til Læderhuden, findes en hel 
Del enkelte pæreformige Legemer. hvis bredere, afrundede 
Del er ligesom -medsænket i Corium, medens den smalere, 
«Stilkede, forlænger sig op imellem Epithelcellerne, Fig. 9, 
6, e. Disse Legemer, der ere 0.006”” lange og 0.0083” 
brede, bestaa af en tynd gjennemsigtig Membran, der 
1 
. Lå 
axovda en Pio og teoyos 
et Hjul. 
brevis agree in the structure of the skin and the wheel- 
shaped spieules 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 vitreus — we refer to 
our description of that organ — was exactly similar to 
that in Myriotrochus brevis; nor does the nervous system 
in the one exhibit any difference whatever from that in the 
otber.. 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 vitreus is 
identical with Myriotrochus (Chirodota) brevis, 
therefore, be added to the list of synonyms. 
and must, 
Acanthotrochus' mirabilis, n. g. 
Pi. V--VI; fies. 8 and 81. 
5 thy Sjø 
Body, measuring 10—12”” in length, cylindric, elon- 
gate, the posterior extremity rounded and somewhat broader 
than the anterior; constricted in the middle. Skin erystal- 
line, its surface dotted with minute lustrous points, which, 
examined under a lens, are found to be wheel-shaped spi- 
cules of characteristic form. Longitudinal muscles 5. 
Twelve digitated tentacula. 
Skin. 
Beneath the structureless eutiele extends the epithe- 
lium, consisting of a single layer of cylindric cells, Pl. V. 
fig. 9, a, webbed to a broad hyaline stratum, fig. 9, », 
in which are seen here and there a few corpuscles of 
connective tissue, some of them oblong, some furnished 
with one or two offshoots, fig. 9, c, c; ‘moreover, 
the .imner 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 pyriform corpuscles, having their broader rounded 
part as it were embedded in the corium, the narrower, pe- 
dunculate portion protending upwards between the epithe- 
in 
lial cells, fig. 9, e,e. These corpuscles. which measure 
1 axavoa, a spike; tooyoc, a wheel. 
