Ihvorvel de nu beskrevne Organer 1 hoi Grad afvige 
fra de hidtil kjendte Pedicellarier, have vi dog benævnet 
dem saaledes, fordi de, efter vor Formening, nærmest maa 
henføres dertil. De konstatere paa det Evidenteste Pro- 
fessor Agassiz’s Iagttagelser, at Pedicellarier ere kun en 
yderligere Udvikling af Pigge; thi ligesom Agassiz har for- 
fulet Piggens Udvikling til Pedicellarie, saaledes kan man 
hos Bathybiaster meget let finde de for denne Udvikling 
nødvendige Overgange. 
Randpladerne, der ere stillede lige overfor hinanden, 
ere 5.07” brede og 2”” høie paa den nærmest Skiven til- 
grændsende Del af Armen paa det største Exemplar; 4.57” 
brede og 2”” høie paa Armens Midte. Deres Siderande 
ere forsynede med en Rad tætstaaende, runde Papiller og 
deres Flader ere overalt bedækkede med fine, næsten flade, 
taglagte Kalkskjæl, Fig. 1. 2. 
De dorsale Randplader have en næsten perpendiku- 
lær Stilling og gaa ikke ind paa Ryggen af Armene; hen- 
imod deres ydre og øvre Rand ere de forsynede med en 
flad Torn, Fig. 2, a. 
De ventrale Randplader, der staa lige overfor de dor- 
sale, have flade Torne; de inderste Plader (nærmest Ski- 
ven) bære 4, der staa i en Række og ere lige lange; læn- 
gere ud paa Armen er der 3 og saa 2, indtil endelig de 
ydre Plader have kun 1 Torn. Ligesom Tornene aftage 
i Antal, saaledes 'aftage de ogsaa i Størrelse, Fig. 2, b. 
Hudskelettet paa Rygfladen er paa hele Skiven sam- 
mensat af temmelig smaa, mere eller mindre runde Plader, 
der ere taglagte, og fra Skiven gaar et bredt Belte af 
lignende Plader langs Armenes Midtparti lige ud til Spid- 
sen, aftagende efterhaanden 1 Bredde. Paa begge Sider af 
dette Belte hen til Randpladerne dannes Skelettet af smaa, 
stjerneformige Plader, der ere taglagte; men paa Grund af 
Udløberne fremkomme et Slags tæt Kalknet med yderst 
smaa Masker, hvori i Regelen er en Tentakelpore, Fig. 12. 
Disse stjerneformige Plader ere paa deres indre Flade kun 
lidet hvælvede, paa deres ydre Flade, Fig. 11, have de en 
ophøiet, aflang Flade, der bærer Paxillen. Hverken paa 
Skiven eller paa Midten af Armene findes Tentakelporer. 
Bugfladens Hudskelet dannes af temmelig store. at- 
lange, taglagte Kalkplader, der i Interbrachialrummene ere 
placerede i regelmæssige Rækker; den udvendige Flade af 
Pladerne har mange smaa, runde Knuder, der bære de 
tidligere omtalte siddende Pedicellarier. 
Ambulacralpladerne udmærke sig ved sine overordent- 
lig brede, bladformige Sideprocesser, paa hvis indvendige 
Flades Midte findes en fremiagende Kam, hvortil den tem- 
melig lange, smale, listeformige Ambulacralstotte (soutien 
ambulacraire) er fæstet. Sideprocessens ydre Flade har en 
større og en mindre Artikulationsflade, der støder til de to 
tilsvarende Adambulacralplader. 
92 
“supports (soutien ambulacraire) are secured. 
Although the organs just described, differ in great 
degree from the pedicellariæ previously known, we have 
still designated them thus, because, in our opinion, they 
are nearest allied to these. They confirm, most conclusive- 
ly, Professor Agassiz’s observations, that pedicellariæ are 
only an extended developement of spines, because, just as 
Agassiz has followed the development of spines into pedi- 
cellariæ, can we, in Bathybiaster, very easily, find the neces- 
sary transition stages for this development. 
The marginal plates are placed right opposite to each 
other, and in the largest specimen, they are 5.5”” broad, 
_ and 2”” thick, at the part of the ray adjoining the disk, 
and 4.5”” broad, and 2”” thick, in the middle of the ray. 
Their lateral margins are furnished. with a series of close 
set papillae, and their surfaces are, everywhere, covered with 
minute, flat, imbricate scales (fig. 1. 2). 
The dorso-marginal plates are situated in a nearly 
vertical position, and do not extend into the dorsal surface 
of the rays. ‘Towards their superior and exterior margins, 
they are furnished with a flat aculea (fig. 2, da). 
The ventro-marginal plates are placed right opposite 
the dorso-marginal plates, and have flat aculeæ. The in- 
ner plates (nearest the disk) carry four aculez of equal 
length, arranged in a series. Further out upon the ray, 
there are three aculeæ, and still further out, two, until, 
finally, the outer plates have only one aculea. Just as the 
aculeæ diminish in number, so do they, also, diminish in 
size (fig. 2, b). 
The dermal skeleton of the abactinal surface, is, upon 
the entire disk, composed of rather small, more or less 
round, plates, which lie imbricate. From the disk, a broad 
belt of similar plates proceeds, extending along the mesial 
line of the rays, right up to the tip, but gradually dimin- 
ishing in size. On each side of the belt, towards the mar- 
ginal plates, the skeleton is formed of small asteriated 
plates, which are imbricate, but by means of the prolonga- 
tions, produce a kind of compact calcareous reticulation 
with extremely fine meshes, in which a tentacular pore is 
usually seen (fig. 12). These asteriated plates, are only 
slightly convexed on their interior surface, but their exter- 
ior surface is arcuate, and oblong, and it carries a paxilla 
(fig. il). Neither upon the disk nor upon the middle of 
the rays are tentacular pores seen. 
The actinal dermal skeleton, is formed, of rather large, 
oblong, imbricate calcareous plates, placed in regular series 
in the interbrachial spaces: The exterior surface of the 
plates, has many smallround knobs, which carry the sessile 
pedicellarize previously spoken of. 
. The ambulacral plates are distinguished, by their re- 
markably broad leaf-formed lateral processes, in the middle 
of whose interior surfaces, there occurs a prominent ridge, 
to which the rather long narrow fillet-formed ambulacral 
The exterior - 
surface of the lateral processes, has a large and a small 
articulatory surface, which butt with the corresponding ad- 
ambulacral plates. 
