of the three posterior pair. These latter are
elongated, not protuberant, and support eight pairs of spines with very
minute intermediate spines; those in the dorsal tufts are numerous and
long.

_Caudal Appendages_ nearly as long as the pedicels of the sixth cirrus;
oval, moderately pointed, with their sides, for one fourth of their
length, thickly clothed with long very thin spines.

_Affinities._--In the form of the scuta and of the carina this species
is most nearly allied to _D. Grayii_ or _D. pellucida_, in the form of
the terga to _D. Warwickii_.

5. DICHELASPIS ORTHOGONIA. Pl. II, fig. 10.

_D. scutorum basali segmento angustiore quam occludens segmentum;
longitudine fere dimidia; duorum segmentorum junctione calcarea:
tergorum prominentiis marginalibus inaequalibus quinque: carina deorsum
in parvo calyce lunato terminata._

Scuta with the basal segment narrower than the occludent segment, and
about half as long as it; junction of the two segments calcified. Terga
with five unequal marginal projections. Carina terminating downwards in
a small crescent-formed cup.

Maxillae with the inferior part of edge much upraised.

Hab. unknown; associated with _Scalpellum rutilum_, apparently
attached to a horny coralline. British Museum.

The specimens are in a bad condition, not one with all the valves in
their proper positions, and most of them broken; animal's body much
decayed and fragile.

_General Appearance._--Capitulum apparently much flattened; valves
naked, coloured reddish, separated from each other by thin structureless
membrane.

The _Scuta_ consist of two bars placed at right-angles to each other,
with the point of junction fully as wide as any part of the basal
segment, and perfectly calcified; the primordial valve lies at the
bottom of the occludent segment. The basal segment is equally narrow
throughout, and very slightly concave within; the occludent segment
widens a little above the junction or umbo, and then keeps of the same
width to the apex, which is obliquely truncated; internally this segment
is concave; externally it has a central ridge running along it; the
occludent segment is twice as long and twice as broad as the basal
segment. Both segments are a little bowed from their junction to their
apices.

_Terga._--These are of a singular shape; they are about three-fourths as
long as the occludent segment of the scuta, and in their widest part, of
greater width than it. The