running parallel with the furrow, and another, placed at right angles to this, forming
a radiating comb, which holds a transverse position in relation to the direction of the
ray. In the innermost or furrow series there are 3 to 4 spinelets to each plate, forming
a line frequently more or less oblique and curved in its position; and their length at the
base of the ray is fully equal to two thirds of the breadth of the furrow at its widest
part. In the transverse series, the spinelets, which are 5-7 in number, are connected
at their base by a membranous skin; they are stout, and the innermost spines are somewhat
larger than those of the longitudinal series.
The interbrachial spaces are very narrow, and either entirely naked or bearing
only a few small spine-groups resembling rudimentary papillae, irregularly disposed here
and there.
The mouth-plates are broad and subtriangular, having a marginal fringe of large
robust mouth-spines upon their outer edges; the four or five innermost, which are directed
towards the actinostome, diverge only slightly from one another; whilst the following
five or six, which are somewhat smaller, radiate sideways, and interlock more or less
deeply with those of the neighbouring mouth-plate. From the surface of each mouth-
plate, and standing perpendicularly thereto, midway between the outer edge and the
median suture, is a secondary series of two or three large robust spines.
Size.—Large examples are on record measuring 280 millims. in diameter; but the
northern specimens are usually very much smaller, seldom'exceeding 100-150 millims.,
the largest individual from Discovery Bay being only 93 millims.
Colour. According to Lfitken the Greenland specimens are generally of a deep
fiery red; but in the more southern portion of its area of_distribution the species "is
frequently more or less mottled with lighter shades, whilst the general .tint is often
inclined to shades of purple. Small examples are white or straw-coloured. All colour
is usually bleached in specimens preserved in spirit.
Habitat.—C. papposus frequents a hard-ground locality, its bathymetrical range
extending from low water to great depths, as indicated in the citations of occurrence
given below.
Premature Form.—In a young stage the ossicles of the abactinal network are more
widely spaced, and consequently the paxilte, which at this age are only found at the
intersections, stand further apart and are fewer in number; whilst the paxilke, although
composed of a smaller number of spinelets, are proportionately larger in size when
compared with those on the adult Starfish. The large compressed lateral paxilke are
fewer in number, as are also the papulse. Consequent on the smaller number of ray-
elements there are fewer transverse ambulacral combs; and these themselves are made
up of only 3-5 spinelets (the number varying according to age), whilst not more than
two spines of the longitudinal furrow-series are present. The mouth-spines are, in like
manner, less striking, both in character and number.
Variations.—The variations which aye the most strikingly conspicuous in this
species are those that affect the relative proportions of the rays to the disk and the
character of the dorsal paxillse. Dr. Lfitken* has already remarked on the existence
* Vid. Meddel. N. Forening i Kjobenhavn, 1857, p. 42.
of a long-armed variety, in which the rays are flatter and more pointed, and the paxillæ
smaller but more numerous. Examples of a similar form occurred in the collections
made during the British Arctic Expedition of 1875-76 ; and there may also be noted in
these specimens an increase in the number of lateral paxillary combs concurrent with
the greater length of the ray.
The number of rays is also subject to variation, the presence of ten especially
seeming to bear a locational significance. Only one example from Greenland is cited
by Lütken ; but amongst the specimens collected in the extreme north by the naturalists
of Captain Nares’s Expedition (mentioned above) this number of rays was the general
rule.
I t would seem probable that the two species established by> Brandt under the
names of Asterias affinis and A. alboverrucosa should be ranked in the present category,
since the characters upon which the specific individuality of these forms is based are,
excepting the number of radii, only those which accompany early phases of growth ;
and this fact, together with the small size of the recorded type (disk 1 inch in diam.),
would go far to warrant the conclusion that (in the case of affinis at least) Brandt’s
species is nothing more than the young stage of the northern ten-armed form of
C. papposus. The description given in the 1 Prodromus Descrip, animalium &c.’ is itself
so brief, that it furnishes no features upon which a contrary opinion can be maintained ;
but at the same time the statement should not be lost sight of that the diagnosis was
founded not upon an actual specimen, but only upon a drawing by another hand.
Obviously, therefore, no great reliance upon the determination can be accorded by, or
even be- expected of, posterity in such a case.
In the recently published memoir by MM. Danielssen and Koren on the Echino-
dermata of the Norwegian North-Atlantic Expedition*, two specimens of Crossaster are
referred to this obscure species of Brandt’s (A. affinis) and carefully described (l. c. p. 57).
It would seem to us, however, that the details there cited may, with perhaps only a
single exception, be shown to occur in forms which can be traced through all the stages
of variation up to the undoubted typical C. papposus, and not unfrequently even in
British examples of the species.
One very marked peculiarity, however, is noted in the description above referred
to, and which consists in the great number of spinelets present in the series on the
furrow side of each adambulacral plate, viz. seven (or even eight rarely); whilst in large
specimens of C. papposus it is very seldom that more- than four occur, and similarly in
the northern ten-armed specimens from Discovery Bay. Such a divergence is very
remarkable. The number of spinelets in the transverse comb is also greater (8-10)
than generally obtains in C. papposus of similar size.
Balancing the whole evidence, however, it would appear very doubtful whether the
divergence is greater than might be expected in a locational or deep-sea variety, and
which we should greatly question the propriety of separating as an independent
species from Crossaster papposus. The specimens were dredged in lat. 64° 35' N.,long.
10° 20' W., 290 fathoms.
* Nyt Mag. f. Naturvidensk. 1877, Bd. xx in . 3, p. 45.