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63
ingen Anledning til at kunne iagttage Hjulformen.
■Trochostoma Thomsonii lever paa Lerbund. og den
fører visselig et meget stille Liv; nogen synderlig Bevægelse
kan den ikke udføre; idetmindste kan den ligge ganske
ubevægelig i Observationskarret i mange Dage, og man
skulde tro, at der intet Liv længere var tilstede, dersom
man ikke af og til saa en Excrementprop komme ud af
Analaabningen, og at de oftere nævnte rørformige
Forlængelser paa Mundskiveri forandrede noget Form. Det er
imidlertid rimeligt, at den ikke vedbliver at leve paa samme
Sted hele Livet igjennem, men at den kan føres ved
Strømninger fra det ene Sted til det andet ; thi meget let kommer
den i en rullende Bevægelse.
Farven er violet, snart lys, snart mørk, spillende
noget i det Brunlige mod Bugfladen. Længdemusklerne ere
skidden gule. Mundskivens rørformige Forlængelser,
ligesom den forreste Del af Kroppen er i Almindelighed
blegviolet. Mundskivens glatte Del og Tentaklerne ere
hvidgule. Den haleformige Forlængelse bleg gul-violet. Paa
et Par Exemplarer var Farven mere grønlig med større og
mindre mørkebrune, næsten sorte Flækker; den haleformige
Forlængelse hvid med et blegt rosenrødt Skjær, og hele
Mundskiven næsten hvid, naar undtages de rørformige
Forlængelser, der vare bleg grønlige.
Findested.
Station 18. Station 33, Station 137.
the rotate part, which are seen more or less to swell. It
frequently happens, however, that a small portion only of
the oral disk makes its appearance, in which case the
rotate form will not ho observed.
Trochostoma Thomsonii affects a clay bottom, and
is unquestionably a very sluggish animal: indeed its capacity
of motion can be but limited; at least it will often keep
motionless for days together when placed in a tub of
sea-water for examination, and life would seem wholly extinct,
were not a faecal pellet seen now and again to pass out of the
anal opening, accompanied by a scarcely perceptible change
in the form of the tubular prolations on the oral disk.
There is however no reason to suppose that this animal
passes the entire period of its existence in one spot, the
force of ocean currents being amply sufficient to float it
from place to place, since it may be easily given a rolling,
swaying motion.
Colour violet, sometimes light, sometimes dark, with
a tinge of brown on the ventral surface. Longitudinal
muscles a dirty yellow. The tubular prolations of the oral
disk, as also the anterior portion of the body, generally
pale violet. The smooth portion of the oral disk and
the tentacles whitish-yellow. The caudiform portion pale
yellowish-violet. In one or two specimens the colour was
more of a greenish hue. relieved with dark-brown, almost
black patches, varying in size. Caudiform appendix white,
faintly tinged with rosy-red, and the whole of the
oral-disk almost white, saving the tubular prolations, which were
pale greenish.
Looality.
Station 18 ; Station 33; Station 137.
Slægtakar akter.
Legemet langt, cylindrisk. Den forreste Ende
tvert–afskaaren. Mundskiven forsynet med 15 rørformige
Forlængelser, afvexlende med 15 aflange Fordybninger, hvori
findes 15 papilformige Tentakler. Den bagerste Ende
hale-formig forlænget. Analaabningen omgivet ai’ 5 Tænder. Huden
meget ru. Ingen Fødder. To Tarmappendices (Lungetræer).
Artskarakter.
Tentaklerne rudimentære, forsynet med 3 smaa
Papiller. hvoraf den midterste er den største. Kalklegemerne i
Huden forskjellig formet, dels ovale, dels elliptiske, dels
større gjennembrudte Plader med Kroner, og hvori
Grundformen er trearmet. Hudens Farve er violet, noget brunlig
mod Bugfladen og lysere i Bag- og Forenden.
Generio Character.
Body long, cylindric; anterior extremity truncate.
Oral disk furnished with 15 tubular prolations. alternating
with 15 oval-shaped depressions, in which are 15 papillary
tcntacula. Posterior extremity caudiform elongate. Anal
opening surrounded by 5 dentelli. Skin exceedingly rugose.
No suckers. Two intestinal appendices (respiratory trees)
Speoiflo Charaoter.
Tentacles rudimentary, furnished with 3 snudl papilla?,
that in the middle being the largest. The calcareous
corpuscles in the skin varying in form and size, some being
oval and some elliptic, and some occurring as comparatively
large perforated plates, each with a corolla, their
fundamental form trifid. or rather three-armed. Colour of
skin violet, tinged with brown on the ventral surface, and
somewhat lighter at the posterior and anterior extremities.
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