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39
fra dens forroste Hand 12 Processer, der have en Retning
indad og fortil; de ere alle brede ved deres Grund og ende
meget spidst. Fig. 15. Imellem disse Processer .lindes
ligesaa mange temmelig dybe halvmaaneformige Indsnit, der
optage Tentaklerne, ^Fig. 15. e.
At de ventrale Stykker af Kalkringen ere større og
have længere Processer, end de dorsale, er noget
Acantho-trochiis har tilfælles med Shegten Myriotrochus, og hvorved
Kalkringen- hos samtlige ere høiere paa Ventral- end paa
Dorsaliiaden.
Vandkarsyatemet.
Vandkarringen ligger bagenfor og indenfor Kalkringen;
deus Hinder ere tynde og gjennemsigtige og ere beklædte
udvendig af det Himrende Peritoneum. Den er noget aflang,
saaledes nemlig, at den gjør en stump Vinkel paa Bugsiden.
Fra Vandkarringen üdgaar 10 Teutakelkar,. 7 paa
Dorsalfladen og Sidefladerne, 3 paa Bugfladen. Den
midterste af disse forbliver udelt; de to øvrige dele sig hver i
2 Grene, der gaa til liver sin Tentakel.*
Den Poliske Blære er aflang og har en meget kort
Stilk; den gaar over i Vandkarringen paa venstre Side af
denne tæt ved Udspringet af det venstre ventrale
Tentakelkar.
Stenkanalen bestaar af en stilket, pæreformig Sa>k,
Fig. 17. i hvis temmelig faste, membra nøse Vægge
iagttages overalt Kalkfletiiinger, Fig. 18. Den blinde
afrundede Ende er fri; den lange stilkede Del munder ud i
Vandkarringen paa dennes lioire dorsale Side. Sækkens
Lumen indeholdt en klar Vædske. Vi have kaldt dette
Organ Stenkanal, omendskjønt det i morphologisk Henseende
afviger noget fra Stenkanalen hos Echinodermerne i
Almindelighed; men der kan ingen Tvivl være oin, at det i
functionel Henseende har den samme Betydning. Fra
Vandkarringens forreste Rand udgaar en tynd Membran,
der gaar op og fæster sig paa Muudskivens Underflade,
hvorved Svælgsinus dannes.
Tentaklerne ere" korte: Skaftet omtrent 1""" langt,
cylindrisk og gjenneuiskinnende, saa at Hulheden tydelig
kan sees, Fig. 19. Bladet er ikke fuldt saa langt som
Skaftet, er haandformigt med 3 tilspidsede Lapper eller
Grene, hvoraf den midterste er den længste, Fig. 19, b. og
begge Sidelapperne have et dybt Indsnit, Fig. 19, c.
Hverken i Tentaklerne eller Mundskiven tindes Kalk.
Blodkarsystemet afviger ikke fra Holothuridernes i
Almindelighed: .kun saa vi ingen Anastomoser imellem
Tarmkarrene, paa de forskjellige Tarmslynger, hvilket ellers
saa hyppigt forekommer.
when the parts composing it are in position, issue,
accordingly, 12 processes, directed-inwards and forwards: they
are all of them broad at the base, and terminate in a
sharp point, flg. 15. Between these processes there are an.
equal number of rather deep lunate incisions, for the
reception of the tentacles, flg. 15. e.
The greater size and length of the processes issuing
from the ventral segments of the calcareous ring, as compared
with those springing from the dorsal pieces, is a feature
shared by Acanthot roehus with the genus Myriotrochus. and
which gives greater height to the calcareous ring on the
ventral than on the dorsal surface.
Aquiferous System.
The water-vascular ring is located posterior to and
within the calcareous ring; the membranes composing it are
thin and transparent, and covered externally by the
vibra-tile peritoneum. In fonn it is somewhat oval, so far at
least as to form an obtuse angle on the ventral side.
From the water-vascular ring proceed 10 tentacular
vessels. 7 on the dorsal surface and the lateral surfaces,
and 3 on the ventral surface ; that in the middle (on’the
ventral surface) is not divided, the remaining two have
each tyvo branches, proceeding to as many tentacles.
The. Polian vesicle is oval, and hasa very short stem;
it passes into the water-vascular ring oil its left side,
in immediate proximity to the origin of the left ventral
tentacular vessel.
The sand-canal consists of a pedunculate.* pyriform
sac, flg. 17, with rather firm, membranous walls, in which
calcareous reticulations are everywhere observed, flg. 18.
The cæcal rounded extremity is free: the long pedicled
portion opens into the water-vascular ring on its right dorsal
side. The lumen of the sac contains a clear fluid. We
have called this organ the sand-canal, though differing
morphologically to a slight extent from the sand-canal in
most other Echinoderms; but there cannot, however, be
the slightest doubt that its functional character is precisely
the same. From the anterior margin of the water-vascular
ring proceeds a thin membrane, extending up on the under
surface of the oral disk, to which it is webbed, thus
forming the pharyngeal sinus.
The tentacles are short; the shaft, measuring about
I mm ju length. is cylindric and transparent, so that the
cavity can be distinctly seen, fig. 19. The palm is not
quite so long; it is pinnate, with 3 acuminate lappets, the
middle one being the longest, fig. 19. b: both the lateral
lappets have a deep incision, fig. 19, v. Neither in the
tentacles nor in the oral disk is there any trace of
calcareous deposit.
The circulatory system does not differ from that
commonly characteristic of Holothurians. we failed, however,
to detect any anastomoses between the intestinal vessels on
the several convolutions of the intestine, a feature so
frequently observed in other species.
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