fra dens forreste Rand 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 findes lige- 
saa 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- 
trochus har tilfælles med Slegten Myriotrochus, og hvorved 
Kalkringen hos samtlige ere høiere paa Ventral- end paa 
Dorsalfladen. 
Vandkarsystemet. 
Vandkarringen ligger bagenfor og indenfor Kalkringen; 
dens Hinder ere tynde og gjennemsigtige og ere beklædte 
udvendig af det flimrende Peritoneum. Den er noget aflang, 
saaledes nemlig, at den gjør en stump Vinkel paa Bugsiden. 
Fra Vandkarrmgen udgaar 10 Tentakelkar, 7 paa 
Dorsalfladen og Sidefladerne, 3 paa Bugfladen. Den mid- 
terste af disse forbliver udelt; de to øvrige dele sig hver i 
2 Grene, der gaa til hver 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 at det venstre ventrale Tentakel- 
kar. | ev , 
Stenkanalen bestaar af en stilket, pæreformig Sek, 
Fig. 17, 1 hvis temmelig faste, membranøse Vægge iagt- 
tages overalt Kalkfletninger, Fig. 18. Den blinde afrun- 
dede Ende er fri; den lange stilkede Del munder ud i 
Vandkarringen paa dennes høire 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 Al- 
mindelighed; men der kan ingen Tvivl være om, at det i 
functionel Henseende har den samme Betydning. Fra 
Vandkarringens forreste Rand udgaar en tynd Membran, 
der gaar op og fæster sig paa Mundskivens Underflade, 
hvorved Svælgsinus dannes. 
Tentaklerne ere korte: Skaftet omtrent 1”” langt, 
eylindrisk og gjennemskinnende, 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. Hver- 
ken i Tentaklerne eller Mundskiven findes Kalk. 
Blodkarsystemet aifviger 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, accor- 
dingly, 12 processes, directed inwards and forwards; they 
are all of them broad at the base, and terminate in a 
sharp point, fig. 15. Between these processes there are an 
equal number of rather deep lunate incisions, for the re- 
ception of the tentacles, fig. 15, e. 
The greater size and length of the processes issuing 
from the ventral segments of the calcareous ring, as compared 
with those sprmging from the dorsal pieces, is a feature 
shared by Acanthotrochus 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-vaseular ring is located posterior to and 
within the caleareous ring; the membranes composing it are 
thin and transparent, and covered externally by the vibra- 
tile peritoneum. In form 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 two branches, proceeding to as many tentacles. 
The Polian vesicle is oval, and has a very short stem; 
it passes into the water-vascular ring on its left side, 
in immediate proximity to the origin of the left ventral 
tentacular vessel. — 
The sand-canal consists of a peduneulate, pyriform 
sac, fig. 17, with rather firm, membranous walls, in which 
calcareous reticulations are everywhere observed, fig. 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 thé water-vascular 
ring proceeds a thin membrane, extending up on the under 
surface of the oral disk, to which it is webbed, thus form- 
ing the pharyngeal smus. 
The tentacles are short; the shaft, measuring about 
[”” in 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, 0; both the lateral 
lappets have a deep incision, fig. 19, c. Neither the 
tentacles nor in the oral disk is there any trace of calcare- 
in 
ous deposit. 
The circulatory system does not differ from that com- 
monly 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. 
