net, paa hvilket den udbreder sig; desforuden udgaar fra 
denne bagerste Rand Ryg- og Bugkarrét. ' 
 Rygkarret,- Fig. 8, n, er i sit Udsprmg meget tyndt, 
løber langs Oesophagus og Maven bag til Tarmens Begyn- 
delse, hvor det bliver noget tykkere, og fortsætter nu sit 
Løb paa Tarmens Rygflade, indtil det naar den nederste 
Del af den sidste Slynge. hvor det bliver tyndere og taber 
sig i Kloaken, Fig. 8, 0,:0: -Paa’ denne Vei -afgiver det 
‘flere Grene til Mave og Mesenteriet. ligesom Tarmens 
Vægge blive rigelig forsynede med Tvergrene, der som sæd- 
vanligt 'anastomosere med de tilsvarende Grene fra Bugkar- 
ret og danne netformige Udbredninger. Rygkarret er ved 
Bindevæv fast bundet til Mave- og Tarmvæggen. ~ 
Bugkarret er bredere end Rygkarret, og har samme 
Lob som dette, kun ender det noget længere fortil paa 
sidste :Tarmslynge. Det afgiver ligeledes Grene til Mave 
og Tarm, og sender fra den ene Tarmslynge over til den 
anden flere Grene, hvoraf enkelte anastomosere med hin- 
anden, Fig. 8, p. Det ovenfor beskrevne cirkulere Blod- 
kar, der omgiver Npiserøret, svarer nogenledes til det Kar, 
Dr. Théel i sin Athandling over Elpidia kalder Céntralkar 
og betragter som Hjerte. Hos Kolga dannes Centralringen 
af et afsluttet Kar med tykkere, fastere og mere muskuløse 
Vægge, end samtlige de Kar. der udspringe fra det, saa 
‘det tør hænde, at det virker som et Hjerte. . 
Nervesystemet. 
'Nerveringen er som hos alle Holothurider placeret 
lige bag Mundskiven, hvortil den er fæstet ved Bindevæv, 
og omgiver Spisergret. Den er bred, noget bugtet eller 
knudet og har et gulagtigt Udseende, Fig. 80. Den afgiver 
mindre Grene til Mundskiven, Svælget og Tentaklerne, Fig. 
30, a, a, a, a; men desforuden udgaa 5 store Stammer fra 
den, nemlig Radialnéryerhe, Fig. 30, 6, b, 0, b,b. Af 
disse. tilhøre 3 Triviet og 2° Biviet. 
Radialnerverne ere bredere ved deres Udspring,. der 
i Regelen findes ved Siden af en Knude eller Udbugthing. 
Fig. 80, c; men blive snart smalere. indtil de naa Mund- 
skivens ydre Rand, hvor de tiltage noget i Tykkelse, idet 
de træde dels imellem Længdemuskelen og Huden, dels 
imellem. denne og Længdekarret, for at gaa bag mod Enden 
af Kroppen. Bredest ere de dog paa Kroppens Midtparti. 
Imedens de løbe. bag. Mundskiven, afgive de flere Grene til 
denne, 1 hvis Hud disse udbrede sig. De to Radial-Ryg- 
nerver give hver to Grene, en til hver af de to store: 
branch .wmds along the osophagus and the stomach to 
.the generative organ. over which it expands; from the 
posterior margin issue, too. the dorsal. and the ventral 
vessels. i 
The dorsal vessel, fig. 8, 2, is exceedingly thin at its 
origin; it passes backwards ‘along the æsophagus and the. 
stomach to the superior extremity of the intestine, where 
a slight dilatation is observed, running from thence 
over the dorsal surface of the intestine, till it reaches the 
extremity of the terminal convolution, to disappear in the — 
cloacum, fig. 8. 0,0. On its course thither it branches 
off to the stomach and the mesentery; the walls of the 
intestine are furnished. with numerous transverse rami-. 
fications. which. as is commonly the case, anastomose 
with the branches from the ventral vessel, terminating in 
reticulated expansions. The dorsal vessel is webbed to- 
the walls of .the stomach and intestine by connective 
tissue. ed EN 
The ventral vessel is broader than the dorsal; it 
extends in the same direetion as the latter, but terminates 
a little farther in advance, on the last convolution of 
the intestine. This vessel, too, sends off branches ‘to the 
stomach and the intestine. and divers ramifications extend 
from one intestinal.convolution to the other, some of which 
anastomose one with the other. fig.8.p. The annular blood- .. 
vessel, described above, encircling the cesophagus, corresponds 
in some measure to the.vessel which Dr. Théel, in his treatise 
on the genus Elpidia, terms the central vessel, performing, as 
he conceives, the functions of a heart. In Kolga, the een- 
tral ring is a closed vessel. haying thicker, stronger, and 
more muscular walls than have any of the vessels pro- 
ceeding from it; and hence, possibly, its action may be re- 
garded as that of a heart. ke a 
Nervous System. 
_ As in all Holothurians, the nervous ring occupies the 
space immediately posterior to, the oral disk, with which it 
is connected by a web of connective tissue, and encircles | 
the æsophagus. * It is broad, ‘slightly moniliform, and of a 
yellowish appearance, fig..30. It furnishes slender ramifi- 
cations to the oral disk, the gullet, and the tentacles, 
fig. 30, a, a, exclusive of which 5 large stems are seen 
to issue from it, viz. the radial nerves, fig. 30. b, b, 
b, b, b. Of these, 2 belong to the bivium, and 3 to the 
‘trivium. dis 
The radial-nerves are thicker at the point of origin, 
which as a rule is contiguous to a nodular expansion, 
fig. 30, but rapidly assume a slenderer form, 
which .is preserved till they reach the exterior mar- 
gin of the oral disk. where a slight dilatation becomes 
Ga 
apparent, as they pass partly between the . longitudinal 
muscle and the skin. and partly between the latter and 
the longitudinal vessel, protending backwards to the term- 
inal. extremity of the trunk. These nerves, however, attain 
their greatest thickness in the medial portion of the trunk. 
