Endelig skulle vi omtale Stenkanalen, 'der ender blindt 
udad, hvor den efter at have perforeret Muskelhuden fæster 
sig til Coriums indre Flade. Stenkanalen er ifølge Théels 
Tagttagelser fri for Kalk og uden Madreporplade; kun en 
Gang mener han at have seet et lille Legeme af 0.02” 
Diameter, og som forekom ham at bestaa af bueformige 
Spikler, der havde sit Sæde paa Stenkanalens øverste Del. 
Vi kunne supplere dette derhen, at paa den yderste (øver- 
ste) Ende af Stenkanalen, der hvor den er fastvoxet til 
Huden, findes smaa bueformige Kalkspikler, der dels ligge 
enkeltvis og ligesom omgive Kanalen, dels ere de noget 
større, ligge samlede og danne Fletninger, der kunne ansees 
for en rudimentær Madreporplade, Fig. 16, a, 16’; hvorvidt 
der i Kalkfletningernes Masker ere Aabninger eller Spalter, 
der føre ind til Kanalen, kunne vi ikke afgjøre; thi Flet- 
ningerne ligge egentlig i det Bindevæv, hvorved Kanalen 
er fæstet til Huden, Fig. 16, a. 
+ 
Sleeten Kolga maa med Hensyn til den Plads, den 
indtager i Holothuridernes Rekke, stilles meget lavt. Den 
er i enkelte Henseender bleven staaende paa Larvestadiet, 
— saaledes aabner Stenkanalen sig udad med en Pore, 
hvorved Vandkarsystemet, ligesom hos Larven, staar i umid- 
delbar Forbindelse med Søvandet, noget der ikke tidligere 
har været paavist hos nogen Holothuride. Ser man saa 
hen til den øvrige Organisation, — saa finde vi: at Vand- 
karsystemet er temmelig ufuldkomment, har kun to Længde- 
kar; at Hudens Bindevæv er gjennemgaaende hyalint, har 
ikke kunnet hæve sig op til en fibrillær Form; at Kalken, 
som findes i den, har Spikelformen, og kun paa et enkelt 
Sted, Mundskiven, og det endog meget sparsomt, antager 
en mere sammensat Skikkelse, nemlig gjennemborede Skiver. 
Det indre Skelet, som bestaar af 5 yderst smaa Kalkstyk- 
ker med fine udløbende Spikler, kan betragtes som rudi- 
mentært, tjener ikke til Støtte eller Fæstepunkt for Længde- 
musklerne; thi dertil er det altfor spædt, og minder om 
Kalkstaphelierne hos Echinodermlarverne. Tarmkanalen er 
ikke forsynet med de Afsondringsorganer, som man har 
kaldt Lunger. Nervesystemet kunde 1 første Øieblik synes 
at staa temmelig høit paa Grund af den Masse Sandse- 
organer (Høreblærer), som findes paa de to Ambulacral- 
nerver; men erindrer man, at det netop er hos en anden 
lavytstaaende Holothuride (Synapta), og hos enkelte Echino- 
dermlarver. at lignende Organer ere fundne, saa forekommer 
det os, at denne Særegenhed ved Nervesystemet ikke kan 
give Anledning til at sætte Slægten Kolga høiere op 1 
Rangen. Naar man ser hen til den overordentlig store 
Mængde af det nævnte Sandseorgan, som findes langs Am- 
bulaeralhjernen, saa kunde man fristes til at spørge, om 
disse Organer virkelig staa i Hørelsens Tjeneste; thi det 
er ikke godt at forstaa, at et saa lavtstaaende Dyr skulde 
være saa rigt udstyret for Sandsningens Vedkommende. 
19 
In conclusion, we will briefly notice the sand-canal. 
which, exteriorly, has a cecal termination, at the point 
where, after piercing the muscular layer, it is webbed to 
the inner surface of the corium. According to Dr. Théel, 
the sand-canal exhibits no trace of calcareous deposit, nor 
is it furnished with a madreporic body; once only does 
he believe to have detected a minute corpuscle, 0.02"” in 
diameter, composed apparently of arcuate spiculæ, near the 
upper extremity of the stem. This observation we are 
enabled to supplement, in so far as the superior termina- 
tion of the sand-canal, where it is connate with the skin, 
exhibits numbers of minute, arcuate calcareous spicule, 
some disposed singly, and, as it were, circumscribing the 
stem, the others, somewhat larger in size, being laced 
together, forming a spiniferous network, which may be re- 
garded as a rudimentary madreporic body, fig. 16, a, 16’; 
but whether the meshes of this calcareous network assume 
the form of more or less circular openings, or of fissures, 
we are unable to determine, the network lying embedded 
in the layer of connective tissue that webs the stem to the 
integument, fig. 16. a. 
As regards its position in the scale of organic de- 
velopment, the genus Kolga ranks very low among the 
Holothuriidee. In several respects indeed it has not emerged 
from the larval stage: thus, for instance, the sand-canal 
opens exteriorly through a pore, with which the aquif- 
'erous system communicates directly with the sea-water, a 
characteristic feature not previously observed in any Holo- 
thurian. Glancing further at the anatomical structure of 
the animal, we find the aquiferous system, which is rather 
simple in development, furnished with two longitudinal 
vessels; the connective tissue of the integument, too, is 
hyaline throughout, exhibiting nowhere traces of having 
attained a fibrillous character; moreover, the calcareous de- 
posit it contains is of the spicular form; on one part only 
of the organism — the oral disk, and even there to a 
limited extent, does it assume a more complex structure. 
occurring as perforated laminæ. The inner skeleton, which 
consists of 5 exceedingly minute calcareous plates, with 
slender protending spicule, may be regarded as rudimen- 
tary, since it does not serve to strengthen the longitudinal 
muscles, or to furnish them with a point of attachment: 
indeed it is far too fragile, bearing considerable resemblance 
to the calcareous stapheliæ in the larval forms of Echi- 
nodermata. The intestinal canal is not provided with the se- 
cretory organs which have been termed respiratory trees. At 
the first glance the nervous system does indeed seem to be 
highly developed, by reason of the large numbers of sen- 
soria (auditory vesicles) on the two-ambulacral nerves; but 
if we call to mind that similar organs occur in. another 
low-organized Holothurian (Synapta), and in a few larval 
forms of Echinodermata, this peculiar feature in the ner-. 
vous system is, we conceive, quite inadequate as a reason 
for placing the genus Kolga higher up in the scale of 
structural development; nay the immense number of 
these sensoria is in itself suspicious; it would seem to 
warrant our doubting their alleged subservience to the 
ox 
5 
