elegantly spinulated. In colour the perisom passes
from a dark rose on the surface of the disc and along
the upper surface of the arms, through paler shades
to a nearly pure white on the under surface.
This haul yielded, along with Opliiacantlia chelys,
the beautiful little Opiiiurid represented in Pigs.
18 and 19. The diameter of the disc is 5 mm., and
the arms, which are rather wide at the base and taper
I
F ig. lS .—OpMoimmum pnlchelhm, Wyvm.le Thomson, Dorsal asiiect of the disc Seven
times tlie jia tu ra l size. (No. 87.) ■
rapidly, are only about once and a half the diameter
of the disc in length. The upper surface of the disc
is very regularly paved with thick, Avell-defined plates,
each of which rises in the centre into a pointed
tubercle approaching a spine in character. One
almost regularly hexagonal plate occupies the centre
encircled by a roAV of six plates of the same form ;
