Trochostoma (Molpadia) boreale, M. Sars. 
Syn. Molpadia violacea, Studer? 
(Tab. X, Fig. 7—11). 
I vor tidligere Afhandling over Trochostoma Thom- 
soni ytrede vi den Formening, at Sars’s Molpadia borealis 
maatte blive at henføre til den af os opstillede Slægt 7o- 
chostoma, da den efter Sars’s Beskrivelse ikke kunde være 
nogen virkelig Molpadia. Fra Christiania Universitets Sam- 
linger have vi faaet udlaant Resterne af Sars's Original- 
exemplarer, nemlig endel Hud, noget af Tarmkanalen og 
Kjønsorganerne, hvorved vi ere blevne satte istand til at 
anstille Undersøgelser og Sammenligninger, der have bragt” 
os til fuldkommen Vished om, at Sars's Art ikke er nogen 
Molpadia, men Trochostoma. Vi have ogsaa derved 
faaet Anledning til dels at berigtige, dels at supplere Sars's 
en 
Beskrivelse. 
Med Hensyn til de ydre Karakterer skulle vi be- 
mærke, at den haleformige Forlængelse har rundt Kloak- 
aabningen 5 Papiller (Tænder), lig dem hos Troch. Thom- 
sont, hvilke have undgaaet hans Opmærksomhed. 
Hudens histologiske Sammensætning er ikke forskjellig 
fra den hos Tr. Thomsomii, derimod ere Kalklegemerne, 
som ere leirede i Bindevævslaget., 
Grundformen er den samme. 
forskjellige, om end 
De fremtræde under to Hoved- 
former og i forskjellig Størrelse, nemlig de smaa, der ere 
dels elliptiske, dels mere. eller mindre runde, — og de 
store, der ere mere sammensatte. 
De elliptiske eller aflange, Fig. 7, a, 10, ligge tæt 
til hverandre og tildels paa hverandre, have en smuk vin- 
rød Farve og bestaa af temmelig regelmæssige concentriske 
Ringe, der danne Lag, Fig. 10, imedens de mere runde 
Kalklegemer, Fig. 11, have en gul Farve. ere mere ujævne, 
bestaa ligeledes af Lag, men ikke saa regelmæssige. og ere 
sammenhobede imellem de elliptiske. Saavel disse som de 
runde danne ligesom et sammenhængende Lag, ovenpaa 
hvilket de store Kalklegemer hvile. Disse ere noget for- 
skjellige, alt eftersom de findes paa de forskjellige Legems- 
dele, men den trearmede Grundtype gjenkjendes dog. Paa 
begge Ender af Legemet ligge de temmelig tæt til hver- 
andre; Kalkpladerne ere her langstrakte med en Udløber 
til hver Side, og fra Midten af den af Huller gjennembrudte 
Plade hæver sig Skaftet, eller Kronen, der ved sin Grund- 
del er trearmet, men forøvrigt rundt, og udvider sig noget 
i den frie Ende, som er forsynet med flere Takker, Fig. 8. 
1 Dr. Th. Studer, Ueber Echinodermen aus dem antarctischen 
Meere. Monatsberichte der kön. preuss. Academie der Wissenschaften 
m Berlin. 1877, Pag. 454. 
64 
Trochostoma (Molpadia) boreale, M. Sars. 
Syn. Wolpadia violacea, Studer?! 
(Pl. X, fies. 7—11). 
In a previous Memoir treating of Trochostoma Thomsonii, 
we expressed as our opinion that Sars’s Molpadia borealis 
would have to be referred to the genus Trochostoma, since, 
according to Sars’s description, it could not possibly be a 
true Molpadia. From the Zoological Collection in the 
University of Christiania we bave obtained on loan all that 
was left of Sars’s original: specimens, viz. fragments of the 
skin, of the intestinal canal, and of the generative organs, 
which has enabled us to institute a series of comparative 
observations: and the results obtained afford to our minds 
conclusive proof that Professor Sars’s species is not a Mol- 
padia, but a Trochostoma. While conducting the examina- 
tion, we have also had an opportunity of amending and 
supplementing Sars’s description. 
As regards the external characters of the animal, we 
must not fail to observe that the caudiform appendix is 
furnished round the anal opening with 5 papillæ (teeth), 
similar to those in Trochostoma Thomsonii, a feature not 
detected by Sars. 
The histological structure of the integument is the 
same as in Tr. Thomsonii; the calcareous corpuscles, how- 
ever, embedded in the layer of connective tissue, though 
the trifid form is fundamental in both, exhibit certain 
differences. * Varying as they do in size, we may divide 
them into two groups, one comprising the small corpus- 
cles, some of which are elliptic and some more or less 
globular, and the other the large corpuscles, distinguished 
by a more complicate structure. | 
The elliptic-shaped, or oblong corpuscles, fig. 7, a, 10, 
exhibit a close arrangement, lying one beside, nay fre- 
quently upon, the other are of a beautiful vinous red, and 
composed of comparatively concentric rings, forming layers, 
fig. 10; the corpuscles approximating more a circular 
form, fig. 11, are yellow in colour and not so smooth, but 
also consist of layers —‘less regular however — and lie 
crowded together between the elliptic-shaped corpuscles. 
Both forms, the elliptic and the round, constitute each, as 
it were, a continuous layer, upon which the large corpus- 
cles are disposed. The latter vary somewhat in form: ac- 
cording to the part of the body on which they occur; they 
all, however, retain the trifid, three-armed type. At the 
extremities of the body their arrangement is comparatively 
close; here, the calcareous plates are elongate, with an off- 
shoot on either side; and from the middle of the perforate 
plate, pierced with numerous holes, springs the shaft, or 
corolla, which at its base is three-armed, but. elsewhere 
cylindric; at its free extremity, furnished with several 
spikes, it slightly expands, fig. 8. 
1 Dr. Th. Studer, Ueber Echinodermen aus dem antarctischen 
Meere. Monatsberichte der kin. preuss. Academie der Wissenschaften 
zu Berlin, p. 454; 1877. 
