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are a t first undistinguisliable from young primary
spines ; tbe iirst set look enormously large in proportion
to the other appendages of the perisom. Almost
simultaneously Avith the first appearance of the
primary spines, ten tentacular feet, apparently the
hrst pairs on each ambulacrum of the corona, just
beyond the edge of the peristome, come into play ;
they are A'ery delicate and extremely extensile, Avith
AA'ell-detined sucking-disks ; and AA'ith these the young
cling to and move over the spines of the mother, and
cling to the sides of the glass vessel, if they are dislodged
from the marsupium. This species seems to
acquire its full size during a single season. AAY
dredged it at the close of the breeding season, and Ave
took no specimens intermediate in size betAveen the
adult and the young.
Among the marine animals Avhich Ave dredged from
the steam-pinnace on the 19th of January, 1874, at
depths of from 50 to 70 fathoms in Balfour Bay (a fine
recess of one of the many channels Avhich separate the
forelands and islands at the head of Royal Sound,
Kerguelen Island), there Avere several examples of
a small Cidaris, Avhich I aaI I I name provisionally
C. nutrix (Fig. 42).
This species resembles (7. papillata in the general
form and arrangement of the plates of the corona, in
the form and arrangement of the primary tubercles
of the interamhulacral areas and of the secondary
tubercles over the general surface of the test, in the
form of the plates of the apical disk and of the imbricated
calcareous scales of the peristome, in the form,
sculpture, and proportionate length of the primary
spines, and in the form of the different elements of the
jaw-pyramid and in th at of the te e th ; but the test is
more depressed, the secondary spines Avhich articulate
to the amhulacral plates and cover the pore-areas are
longer and more cylindrical, not so much flattened as
Fir., i i . —Cidaris n u trix , W y v i l l e T i i o m s o s . Balfour Bay, Kerguelen Island.
Natural size,
they are in C. papillata ; the large tulip-like pedicellariæ
and the long th in tridactyle pedicellariæ mixed
Avith the secondary spines in the northern species are
Avanting, or in very small number ; and the minute
pedicellariæ of the peristome are much feAA'cr. The
ovaries, Avbicli in C. papillata: luiA'e tbe walls loaded
Q 2