Den ydre Hud, der er halv gjennemsigtig og paa 
Overfladeu forsynet med en Mengde haarde, spidse Papil- 
ler, som Følge af de 1 den imsererede Kalknaale, Fig. 1, 
forlænger sig udover Interbrachialrummene lige til Arme- 
nes Spids, hvor den gaar over i Bugfladens Hudbedæk- 
ning. Denne danner imellem Armene en næsten vandklar 
Hud, der holdes udspændt af lange Kalknaale og udgjør 
Bunden i det føromtalte Hulrum, Fig. 6, a, dog saaledes, 
at mderst ved hver Armrand findes en Række halvmaane- 
formige Aabninger, Fig. 2, hvorved Hulrummet korrespon- 
derer med det ydre Medium. Huden paa Ryg- og Bug- 
fladen er i den fri Rand af Interbrachialrummet sammen- 
voxet i et Par Millimeters Bredde, hvorved den her faar 
nogen Lighed med en Svømmefinne. 
på 
Den indre Hud, der er temmelig tynd, dækker den 
øverste Del af Maven med dens Blindtarme samt Ægge- 
stokkene og forlænger sig udover Armenes Ryg, som den 
ganske beklæder; nu bliver den yderst tynd, idet den gaar 
over paa Bughuden, hvor den giver denne med dens lange 
Naale et fuldstændigt Overtræk. En Fortsættelse af denne 
Hud danner en meget tynd og gjennemsigtig Membran, 
der beklæder samtlige Paxiller. 
I Centrum af Hulrummets Bund findes Analaabnin- 
gen, Fig. 7,4, der er lidt aflang og noget fremspringende, 
forsynet med en Sphincter og omgivet af 2 store, noget 
aflange Kalkplader, Fig. 7, b, og 8—16 mindre, lignende, 
Fig. 7, c, hvilke alle ligge paa den underste Flade af den 
indre Ryghud. De to store Plader, der ligge en paa hver 
Side af Analaabningen, nærme sig med deres ydre, afrun- 
dede Rand til de to første Ambulacralplader paa de til- 
grændsende Arme; de øvrige, mindre ligge i to adspredte 
Grupper. Dette Analfelt begrændses udad af en Kalkring, 
der dannes af 5 Interbrachialstykker, Fig. 7, d, d. 
Enhver Interbrachialplade bestaar af en Midtdel, der 
er smal, lang og flad, strækker sig fra den øverste Del af 
Ryggen og bøiler sig ned imod Bugfladen, Fig. 8, a. 9, a. 
Den er lidt udhulet efter Længden, og fra saavel dens 
øverste som nederste Ende udgaa bueformige Processer, 
Fig. 8, b, c. 9, b, c. De øverste Processer støde til de 
tilsvarende fra de to tilgrændsende, interbrachiale Kalkpla- 
der, hvorved Ringen sluttes, Fig. 7; de underste derimod 
forene sig med lignende Processer fra en anden underlig- 
gende Interbrachialplade, Fig. 7, e, der senere skal be- 
skrives. 
Paa de øverste Processer, Fig. 8, b, støtte sig de 5 
store Paxiller, der omgive Analfeltet, Fig. 7, f. Disse Anal- 
paxiller have en Basaldel, der dannes af 4 lange, lidt bue- 
dannede Rødder, Fig. 8, d, hvoraf de inderste, Fig. 8, e, 
74 
The outer integument is semi-translucent, and is fur- 
nished on the superior surface, with a multitutude of hard 
acuminate papillae; formed in consequence of the caleareous 
needles (Pl. XIII, fig. 1) which are inserted in it. It ex- 
tends beyond the interbrachial spaces, and close up to the 
tip of the rays, at which point, it passes into the integ- 
umental covering of the actinal surface. Between the rays, 
it becomes a nearly pellucid integument held expanded by 
long calcareous needles, forming thus, the base or bottom 
of the chamber already referred to (Pl. XIII, fig. 6, a) 
in such manner, however, that upon each rays margin, 
there is observed at the inmost part, a series of crescent 
shaped openings (Pl. XIII, fig. 2), by which the chamber 
is enabled to communicate with the exterior medium. In 
the free margin of the interbrachial space, the integument 
of the abactinal and actinal surfaces, is conereted, to the 
extent of about 2”” in breadth, and this imparts, some similar- 
ity in appearance, to the fin of a fish. 
The inner integument is rather thin, and covers the 
superior portion of the stomach and attached ceca, and 
also the ovaries; extending then over the abactinal surface 
of the rays, and completely covermg them. In passing over 
into the actinal surface, it becomes extremely thin, and 
completely encases it, as well as, the long pertaining ealear- 
eous needles. A continuation of this integument forms a 
very thin and transparent membrane, which clothes all 
the paxillæ. 
The anal opening appears in the middle of the base 
of the chamber (Pl. XIII, fig. 7, a). It is slightly oblong and 
somewhat prominent, and is furnished with a sphincter; it 
is also surrounded by two large, somewhat oblong, calear- 
erous plates (Pl. XIII, fig. 7,0) and also, with 8—16 sim- 
ilar but smaller plates (Pl. XIII, fig. 7, c) all of which 
rest on the inferior surface of the imner dorsal integument. 
The two large plates, which are placed one on each side 
of the anal aperture, approach with their exterior rounded 
margin, to the two anterior ambulacral plates of the adjoin- 
ing rays, whilst, the other smaller plates are situated in 
two separate groups. This anal aperture is bordered, ex- 
teriorly, by a calcareous ring, formed of five interbrachial 
ossicles (Pl. XIII, fig. 7, d, d). Hach interbrachial plate 
consists, of a narrow, long and flat mesial portion, extend- 
ing from the superior dorsal part of the animal, and eurv- 
ing downwards towards the ventral surface (Pl. XIII, fig, 
8, a. 9, a). It is slightly hollowed, lengthwise, and are- 
uate processes proceed from both its superior and inferior 
extremities (Pl. XIII, fig. 8, 0, c. 9, b, c). The superior 
processes butt with the corresponding processes of the two 
adjoining calcareous interbrachial plates, and thus complete 
the ring (Pl. XIII, fig. 7). On the other hand, the in- 
ferior processes unite to similar processes from another 
interbrachial plate placed beneath (Pl. XIII, fig. 7, e), 
and which will subsequently he described. 
The five large paxillæ which surround the anal area 
(Pl. XIII, fig. 7, f) butt with the superior processes (PI. 
XIII, fig. 8, 6). These anal paxillæ have a basal part, 
formed of four, long, somewhat arcuate roots (PI. XIII, 
