strømmet Nøvand, men maa have faaet det paa endosmotisk 
Vei, noget der jo er meget almindeligt for organiske Mem- 
braner. Kommer nu hertil, at de forgrenede Rør hos Tro- 
chostoma ikke ere forsynede med særegne Blodkar, formene 
vi, at de mangle alle Betingelser for at kunne faa Navn 
af Lunger. 
Det forekommer os, at de foreliggende Kjendsgjernin- 
ger paa det Bestemteste maa fraskrive disse Organer al 
Ret til at ansees for at staa i Aandedrættets Tjeneste, men 
at de meget mere maa anses som Afsondringsorganer, der 
tilhøre Tarmen, og forsaavidt formene vi for Trochostomas 
Vedkommende at have bevist Rigtigheden af Johannes Miil- 
lers og Gegenbauers Antagelse, den nemlig, at de saakaldte 
Lunger ere analoge Organer til de interradiale Blindrør 
hos Asteriderne. Men forholder det sig saa hos Slægten 
Trochostoma, saa er der liden Grund til at antage, at For- 
holdet er anderledes for de selysamme Organer hos de oy- 
rige Slægter af Lunge-Holothuridernes store Gruppe. Vort 
Dyr staar unægtelig paa et temmelig lavt Trin i Familien 
og tør derfor ogsaa i 
phylogenetisk Henseende have sin 
Interesse. 
Det indre Skelet. 
Kalkringen dannes af 10 Stykker. 5 radiale og 5 
interradiale, hvilke ere sammenbundne med en stærk Binde- 
vævsmasse, Tab. VIL, Fig..5. Hos unge Dyr er denne 
temmelig svag, saa at Stykkerne med Lethed kunne skilles 
fra hverandre, imedens Forbindelsen hos udvoxne Dyr er 
saa stærk, at den kun kan hæves ved Kniven eller ved 
Hjælp af en koncentreret Kalilud. 
Radialstykkerne ere 5”” lange, 3”” brede paa Midten, 
og ere ikke ganske symetriske, forsaavidt det ene kan være 
lidt smalere og lidt skjævere end det andet, Tab. VII, Fig. 
5, a, a, a. Hvert Radialstykke har en bredere Del, som 
danner det egentlige Legeme (Corpus), Fig. 5, 0, b, 6, b, 
og en Forlængelse (Processus), Fig. 5. a, a, 6, a. Lege- 
met har en udvendig og en indvendig Flade, to Sideflader 
og en øverste Rand. Den udvendige Flade er lidt konvex 
mod Siderne og forsynet med 3 fremspringende Kamme 
(Cristæ); de indtage. hele Fladens Længde og divergere 
lidt nedad, Fig. 5, c. Den midterste Kam er den mest 
fremragende; Sidekammene udgjøre egentlig Siderandene, 
og blive først tydelig fremspringende, idet den ene Rand 
føles til en anden fra det tilsvarende Radialstykke. Imel- 
lem disse tre Kamme to temmelig dybe Furer, 
hvoraf den ene — den udvendige lukkes foroven 
og danner her den skeformige Grube, hvori insererer sig 
den fælles Tendo for to Længdemuskler, Fig. 5, d, d. I 
den indyendige Fure, der altsaa findes mellem Midtkammen 
og den venstre (indvendige) Kam, ligger en Ampulla, Fig. 
5, e. Den venstre Kam rager lidt over den øvre Rand, 
saa at denne derved faar et halvmaaneformigt Indsnit, 
Fig. 6, c. Den indvendige Flade er lidt konkav mod Si- 
ere 
54 
The tubes with their vesicles cannot therefore derive their 
contents from an influx of sea-water; the presence of the 
fluid must be traced to endosmotic action, which indeed 
is very frequent in organic membranes. Moreover, the 
ramose tubes in Trochostoma are not even provided with 
special blood-vessels, and hence, we think, they fail to 
exhibit any one of the features that would entitle them to 
the name of respiratory organs. ; 
The facts we have adduced furnish, in our opinion,- 
the strongest presumptive evidence that these organs. are 
nowise subservient to respiration, but should rather be re- 
garded as secretory organs proceeding from, and belonging to, 
the intestine; and hence, so far at least as concerns the genus 
Trochostoma, we believe to have substantiated the correct- 
ness of Johannes Miiller's and Gegenbauer’s assumption, viz., 
that these “lungs” are organs analogous to the interradial 
cæca-like tubes in the Asteridw. But if this be the case 
with Trochostoma, the function of the selfsame organs in 
other genera belonging to the great group of lung-respiring 
Holothurians must surely be identical. The animal here 
described ranks low in the family Molpadide, and may 
therefore, phylo-genetically, prove an interesting acquisition. 
4 
‘The Caleareous Skeleton. 
The calcareous ring is composed of 10 segments -— 5 
radial and 5 interradial, webbed together byfa compact mass 
of connective tissue, Pl. VII, fig. 5. In young examples, 
the tissue is rather fragile, and the segments readily admit 
of being parted, but in full-grown individuals they adhere 
so tenaciously that a knife. or a concentrated solution of 
potash, is needed to dissolve the connexion. 
The radial segments are 5”” long, 3”” broad in the 
middle, and not quite symmetrical, some being a trifle narrower 
and more oblique than others, Pl. VII, fig. 5, a, a, a. 
Each of the radial segments has a broad part, which con- 
stitutes the body (corpus), fig. 5, b, b, 6, b, and an elonga- 
tion, or process, fig. 5, a, a, 6, a. The body has an outer 
and an inner surface, two lateral surfaces, and an upper 
margin. ‘The outer surface — slightly convex towards the 
sides — is furnished with 3 projecting combs (cristæ), which 
occupy the whole length of the surface, diverging slightly 
downwards, fig. 5, c. The middle comb projects most: the 
lateral combs constitute, strictly, the lateral margins, and do 
not assume a projecting appearance till one margin unites 
. with another from the corresponding radial segment. Between 
these three combs extend two rather deep grooves, one of 
which — the outer groove — is closed above, forming a 
spoon-shaped socket, from which springs the tendon com- 
mon to two of the longitudinal muscles, fig. 5.d,d. In the 
inner groove, extending accordingly between the middle and 
the left (the inner) combs, is seen an ampulla, fig. 5, e. 
The left comb projects slightly above the upper margin, 
producing therein a lunate incision, fig. 6, c. The inner 
surface is slightly concave towards the sides, and exhibits 
