Variations.—The preceding remarks respecting the resemblances that occur in
the premature phases of three allied species (two of which at least are associated in
the same waters) are of themselves sufficient to suggest the existence of ancestral
affinities; and, indeed, so near is the relationship in one case that, although the impracticability
of uniting the whole group is clearly apparent, the propriety of merging
two of them, Ps. Fabricvi and Ps. squamatus, is, in our opinion, far from questionable;
for that Ps. Fabricvi is in reality the outcome of locational variation from the
squamatus type there would seem to be but little doubt. At the same time it is
interesting to note the wide area over which the forms are found distributed and their
divergence maintained—both Ps. phantapus (teste Sars) and Ps. Fabricvi (teste Ayres)
being found on the E. coast of North America, and having associated with them two
allied forms, viz. Ps. Icevigatus, Ayr., and Ps. granulatus, Ayr., both of which may,
without much difficulty, be regarded as derivative forms when the whole group is
passed in review.
Distribution.
a. Greenland: Holsteinborg, lat. 66° 56' N. (* Valorous ’ Doped.); Jakobshavn,
Julianshaab (Lutlcen).
b. North o f American Continent: Newfoundland (Lutken); Grand Manan, 2-8
fms., adhering to rocks (Verrill); Massachusetts Bay.
c. % North o f Duropean Continent: Lat. 74° 48' N., long. 69° 26' E. ( Weypreclit &
Payer's Doped.), the most northern locality on record.
Description o f the Illustrations o f this Species on Plate I.
Fig. 9. Dorsal aspect of the animal: natural size.
10. Ventral aspect of the same specimen: natural size.
11. Ventral aspect of a young specimen: natural size.
12. One of the small cup-like spicules of the ventral integument: magnified,
18. Spicules of the ventral integument: magnified.
Chirodota ljsvis (Fabricius), Grube. Plate I, Figs. 14-19.
1780. Holothwria Icevis, Fabricius, Fauna Greenland«», p. 353. no. 345.
1806. ? Holothuriapellucida (Yahl), Rathke, Zool. Dan. vol. iv. p. 17, tab. cxxxv. fig. 1.
1829. Chirodota discolor, Escbscholtz, Zool. Atlas, Heft ii. p. 13, tab. x. fig. 2.
1833. Pmtacta Icevis, Jager, De Holothuriis, p. 13.
1833. Pmtacta pellucida, id. ibid.
1834. Cucumaria Icevis, Blainville, Manuel d’Actinologie, p. 195.
1834. Cucumaria pellucida, id. ibid.
1835. Dactylota Icevis, Brandt, Prodr. Descrip, anim. ab Mertensio obs., faso. i. p. 45.
1835. Dactylota pellucida, id. ibid.
1835. Chirodota discolor, Brandt, loc. cit. p. 59.
1837. Pmtacta Icevis, Lamarck, Anim. s. Vert. ed. 3, vol. i. p. 553.
1837. Pmtacta pellucida, id. ibid.
1851. ? Thyonidium pellucidum, Sars, Reise i Lofoten og Finmarken, p. 44.
1851. ? Synapta coreacea, Agassiz, Proo. Amer. Acad. vol. ii. p. 269.
1851. ? Synapta rotifera, Pourtales, Proc. Amer. Assoc. Adv. Sci. 1851, p. 15.
1851. CMridota. tarn, Grube, Middendorffs Sibirisohe Eeise, Bd. ii. p. 41.
' 1851. ? Ohiridota discolor, Grube, Miadendorff’s Sibirisohe Beise, Bd. ii. p. 85.
1852. Trochinus pallidus, Ayres, Proc. Boston Soo. Nat. Hist, vol. iv. p. 243.
1853. Ohirodota Imis, Stimpson, Mar. Invert. Grand Manan, p. 17.
1857. Ohiridota lane, liitken, Vid. Meddel. N. Forening i Kjobenhavn, 1857, p. 16.
1861. ? Ohirodota pdlacida, Sars, Oversigt at Norges Eohinodermer, p. 124, pis. 14-16.
1862. Chirodota lams, Bujaxdin & Hupd, Hist. Nat. Zoopb, Hehinodermes, p. 616,
• 1866. Chirodota lane, Terrill, Proceed. Boston Soo. Nat. Hist. vol. x. p. 354.
1867. Chirodota pellucida, Selenka, Zeiteoh. f. wiss. Zool. Bd. xvii. p. 866.
1867. ? Chirodota tigillvm, Selenka, ibid.
1867. ? Chirodota typica, Selenka, ibid.
1868. Chirodota Icevis, Semper, Holotburien, Reise im Archip. d. Phil. PP- 23, 267.
1868. Chirodota pellucida, Semper, Holothurien, Reise im Archip. d. Phil. pp. 23, 267, pi. v. fig. v
Body elongate and cylindrical, to which the absence of sucker-feet and of all
hooklets or asperities imparts a strikingly vermiform appearance. Specimens preserved
in spirit, however, are extremely contracted and generally contorted out of all natural
shape, The skin is smooth, whitish, and semitransparent in spirit preparations; and
the longitudinal muscles form five dense white bands extending from end end and
prominently marking out the interradial spaces. Within these areas are found a
number of milk-white spots or sac-like papillse, ranging up to a millimetre in diameter,
and arranged in three of the interradia (which may be regarded as the dorsal area) m a
fairly continuous line of about 20 to 30, whilst in the remaining two interradia, which
form the ventral surface, there are not more than from 3 to 12, and these confined
generally to the extremities, principally the anterior one. The white excrescences or
sacculi are not all of uniform size; for a smaller one frequently alternates with a larger;
and they contain a collection of the elegant wheel-shaped spicules which characterize
this genus; and of these there may be as many as 90 or even more in the large
spots. The wheels measure 0-1 millim. in diameter, and are uniformly six-rayed; the
edge of the rim is bent over inwards and finely denticulated, a character which is only
perceptible under certain methods of illumination; and this, as well as the manner in
which the “ spokes ” are attached to it, seems to have been frequently misunderstood,
and to have given rise in consequence to much diversity of opinion, since the differences
were considered to be of specific importance.
The tentacles are twelve in number, and somewhat hand-shaped; and the aigita-
tions, of which there are 10-12, are capable of being closed m upon the “ palm. The
tentacles contain a few small spicules, which in the “ fingers” are little more than
simple elongate bodies; but nearer the base their extremities are enlarged and frequently
either cleft or crenulate.
The mouth-ring is very compact, the elements being in such firm adherence as to
convey the idea of a solid annulus; they are subquadrate in form, having the lower
margin incurved, and on the upper a slight prominence with a small hollowing-out of
the margin on either side of it; five of the pieces (alternately placed) are punctured for
the nerve. On the unpunctured plates there is an elevation or crest-like prominence,
somewhat in the form of an inverted T.