outwards. The ambulacral spines are stout and cylindrical, two to each ambulacral
plate; and every pair radiating at the same angle, a regular double row is formed on
both sides of the furrow.
Variations.—The number of rays is very constant at six, although examples having
only five are occasionally met with.
A considerable amount of variability occurs in the spinulation of the dorsal surface.
In some specimens the spinelets axe densely grouped, in others well spaced and with
the encircling pedicellarise more conspicuously displayed. The spines themselves are
either cylindrical, with tips sharply pinched together, or fairly clavate and resembling
in character the spinelets of A. violaceum, O. F. Müller. It would seem that these
differences exist irrespective altogether of age or growth.
Similarly variable in character appears the arrangement of the ambulacral spinelets,
as indicated by the deviation from the regular double row on either side the furrow to
the fourfold series produced by the greater divergence of the alternating pairs. In fact,
we are disposed to believe that the two modes of arrangement may be present on a single
individual, and that it was probably such a specimen that M. Perrier referred with doubt
to the species under notice, giving at the same time a most admirable and lucid
description, which leaves no doubt as to the correctness of his determination*.
I t may be inferred, from the description given in the ‘ Fauna Grcenlandica,’ that
A. polare and possibly also A. grcmilandicum were merged together by Fabricius under
the designation of Asterias miens; and it also seems highly probable that the Starfish
there named A . minuta is nothing more than a young stage of the present species__an
opinion which Dr. Lütken has already expressed*!*.
The description given by Brandt of A. ochotense, inlffiddendorff’s ‘ Eeise indicates
a range of variation which leads to the assumption that more than one form may be
there included. If such a view be correct, a part of the description there given would
answer well for young forms of A. polare.
Müller and Troschel’s type specimens of this species were also unquestionably
young examples.
Distribution.
a. Greenland : W. coast of Davis Strait, about lat. 70° N. (Sabine) ; Upper Torske
Bank, lat. 67° 50' N., long. 55° 27' W. (‘ Valorous ’ Exped.) ; lat. 66° 59' N., long.
55° 27' W., 57 fms. (‘ Valorous ’ Exped.) ; W. coast of Greenland, lat. 65° N. (Nares’s
Exped.) ; Arksut, lat. 61° 10' N , long 48° 15' W. (Barrett).
b. North, o f American Continent: Labrador (Verrill); St. George’s Bank
35-40 fins.
d. North o f Asiatic Continent ; Ochotsk Bay 1 (under the name of A. ochotense,
Brandt).
* Perrier, Kecherches sur les Pédicdlaîrea et lee Ambulacres des Astéries et des Oursins, 1869, p. 33.
t Vidensk. Meddel. Nafcurh. Forening i Kjôbenhavn for 1857, p. 29.
t MiddendoriFs ‘ Eeise in den aussersten Nordea und Osten Sibériens,’ Bd. i t Th. 1, p. 28.
Description o f the Illustrations o f this Species on Plate II.
Fig. 4. Abactinal aspect of the animal: reduced one half.
5. Actinal aspect of the same specimen: reduced one half.
6. Portion near the middle of a ray, actinal aspect: magnified.
7. Portion near the middle of a ray, abactinal aspect: magnified.
8. A similar portion from the more compactly spinulated variety of this
species: magnified.
Astekacanthion ghuenlandicum (Steenstrup), iAithen. Plate II, Figs. 9 12.
1852. ? Uraster vtdacea, Forbes (non Muller), Sutherland’s ‘ Journal o l a Voyage,’ voL ii. Append, p. coxiv.
1853. Asterias Mulleri, Stdmpson, Syn. Mar. Invert. Grand Manan, p. 14. U >
1864 MUramnfhim Mulleri, Sara ?, var., Steenstrup, Vid. Meddel. If. Forening i Kjobenhavn, 1854, p. 240,
1857. Asteracanihiem grccnlandicus, Lutken, Vid. Meddel. N. Forening i Kjobenhavn, 1657, p . f h
18"63. Asterias grcenlandica, Stimpson, Proc. Acad. N. Sd. Philad.. 1*863, p. 142.
1866. Asterias grcenlandica, Verrill, Proo. Boston Soe. Nat. Hist, voh x. p. 357,
| 1 | | l866. Asterias gronilandicus, Gray, Synop. Spec. Starfish Brit. Mus. p. 2.
This species maintains a small habit, with five moderately thick arms, the proportion
of disk-radius to arm-radius being 1:4-5 or 5. The ambulacral spines are rather
long and cylindrical, and stand, in very irregular alternation, two and one to eachadam-
bulacral plate, the single spinelets having a position vertical to the floor of the furrow,
whilst the pairs, on the other hand, radiate apart from one another in opposite direc.
tions Except in young individuals, or near the extremity of the ray, the pairs are more
numerous than the isolated spinelets, and are generally borne by two or three plates in
succession, some rays even being regular for nearly half their length. The lateral spines,
which occupy the sides of the ray, form, according to age, either two or three longitudinal
series of isolated spinelets, not quite so long as the ambulacral senes, and tapering
slightly at their tips—the middle series, when present, being smaller than the others,
and placed midway upon the lateral imbricating pieces. At the base of each of these
lateral spines are a number of pedicellarise forcipiformes, sometimes grouped and sometimes
forming a more or less perfect encircling wreath, the latter generally upon the
lower series.
The ossicles of the abactinal network that lie in the longitudinal direction of the
ray are much shorter than tho.se that occupy a transverse position; and being of delicate
habit, the membranous interspaces are consequently large, as well as much broader than
long. The dorsal spinelets are finer and shorter than those of the ventro-lateral series,
and axe placed in groups of two or three together at the intersections, whilst isolated
spinelets occupy the intermediate intercalary ossicles, by which means, in consequence
of the above-noted proportions of the elements of the calcareous framework, the character
(although somewhat an irregular one) of a transverse arrangement of spinelets
across the ray is produced. Upon the disk the spinelets are more closely placed ; and
this, in specimens preserved in spirit, gives quite a distinct appearance to that portion of
E 2