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39
Arme. Furepapillerne samt Piggene
paa Armenes Sider stærkt takkede.
No. 4. 10mm Diameter. Den lille til den
store Radius som 1 :5.
Furepapillerne stærkt takkede. 2 Arme lidt
- kortere end de øvrige.
Samtlige Maal ere tagne efter de længste Arme.
I den tidligere citerede Afhandling over Echinodermer
fra Vest-Grønland har Dr. Sladen beskrevet en ny Art af
Pedicellaster under Navn af Ped. palæocrystallus. Ved
nøiagtigt at gjennemgaa hans Beskrivelse, ledsaget af
Tegninger, og ved at sammenholde denne med vore
Undersøgelser baade af Sars’s Originalexemplar, Pedic. typicus, og
af de mange Exemplarer, vi forøvrigt have disponeret over,
ere vi komne til det Resultat, at Pedic. palæocrystallus er
identisk med Ped. typicus, hvilket vi nærmere skulle
begrunde. De Kjendemærker, der skulde adskille Ped.
palæocrystallus fra typicus angiver Sladen at være Følgende:
„Ped. palæocrystallus is of larger size, and the length
of the arm-radius, in proportion to that of the disk (about
5:1), is less than in Ped. typicus, in the largest examples
of which, it is 6l/2 or 6:1. The contour of the arms is
also different in our form, being more tumid on the inner
third, and much more attenuated on the remaining
outward portion of the ray. The dorsal spinelets are
decidedly radio-laminate and somewhat expanded at the tip,
instead of being conical as described in typicus, and the
shaft of the ambulacral spinelet is also denticulate or
serrate. The pedicellariæ in the present species are even of
relatively larger size, and differ in having the contour of
the jaws considerably swollen out about the outer third,
and then tapering rapidly towards the extremity, which is
somewhat truncate. Indeed the general facies of the
appendage is unmistakably distinct from that of the more
southern fonn."
Vi have ovenfor angivet Maalene paa vore
Exemplarer, hentede fra de forskjelligste Lokaliteter, og det vil deraf
sees, at saavel Størrelsen som det indbyrdes Forhold
imellem Skive og Arme varierer temmelig meget. Paa enkelte
Exemplarer vare Armene ved deres Grund tykke, hvorved
disse fik et mere konisk Udseende. De dorsale Pigge havde
paa alle Exemplarer den samme Form, som Sladen
beskriver, og det samme var Tilfældet med Ambulacralpiggene,
hvilket vi tidligere have paavist. Heller ikke have vi, hvad
Pedicellarierne angaar, hverken i Form eller Størrelse
været istand til at opdage nogen Forskjel fra dem, der ere
beskrevne og afbildede hos Sladen.
De Forskjelligheder, der efter Sladens Formening
skulde skille hans nye Art fra Sars’s, ere dels ikke
konstante, dels mangle de ganske, men ere sandsynligvis
opstillede af Sladen paa Grund af en mindre korrekt Beskri-
rays. The furrow-papillæ, also the
spines of the lateral surfaces of
the rays are strongly aculeated.
No. 4. 10mm in diameter. The
proportion of the disk-radius to the
brachial radius is as 1:5. The
furrow-papillæ are strongly
aculeated. 2 rays somewhat shorter
than the others.
The longest ray is the basis of all the above
measurements.
In the previously quoted memoir on Echinodermata
from West Greenland, by Dr. Sladen; he has described a
new species of Pedicellaster, under the designation of
Ped.-icellaster palæocrystallus. By closely studying his
description, accompanied by drawings, and comparing these, with
our observations, both, of Sars’ original specimen
Pedicellaster typicus, as well as the numerous specimens which we have
had at our disposal, otherwise, we have arrived at the
conclusion, that Pedicellaster palæocrystallus is identical with
Pedicellaster typicus, and we shall substantiate this more
fully. The distinguishing features between Pedicellaster
palæocrystallus and Pedicellaster typicus are stated by
Sladen to be the following: —
„Ped. palæocrystallus is of larger size, and the length"
„of the arm-radius, in proportion to that of the disk (about"
„5:1) is less than in Ped. typicus, in the largest examp-"
„les of which, it is 67s or 6:1. The contour of the arms"
„is also different in our form, being more tumid on the in-"
„ner third, and much more attenuated on the remaining"
„outward portion of the ray. The dorsal spinelets are"
„decidedly radio-laminate and somewhat expanded at the"
„tip, instead of being conical as described in typicus, and"
„the shaft of the ambulacral spinelet is also denticulate"
„or serrate. The pedicellariæ in the present species are"
„even of relatively large size, and differ in having the con-"
„tour of the jaws considerably swollen out about the outer"
„third, and then tapering rapidly towards the extremity,"
„which, is somewhat truncate. Indeed the general facies"
„of the appendage is unmistakably distinct from that of the"
„more southern form."
We have stated above, the dimensions of our
specimens, taken from the most different localities, and it will
be seen therefrom, that the size, as well as the mutual
proportion between the disk and the rays, varies a good deal.
In a few specimens the rays were thick at their origin,
and this gave them a more coniform appearance. The
dorsal spines, had, in all the specimens, the same form
which has been described by Sladen, and, as we have
already shown, this was, also, the case with the ambulacral
spines. Neither, have we, in regard to the pedicellariæ,
been able to discover, either in form or size, any difference
from those described and illustrated by Sladen.
The features which in Sladens opinion separates his
new species from Sars’, are, partly, not constant, and partly,
are entirely awanting, and have been arrived at by Sladen,
presumably, in consequence of Sars’ partially incorrect de-
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