inferior angle is coarsely pectinated, with one central spine twice as
long as the others. The distance between the tips of the first and
second main teeth, is greater than between the tip of the second tooth
and the inferior angle.

_Maxillae_ (Pl. X, fig. 12).--These may be described as having their edge
formed into three prominences; or, as having a very wide notch under the
two upper great spines, and with the whole inferior part forming two
prominences. There are, altogether, about twelve pairs of spines, of
which two stand singly on the inferior side of the wide notch under the
two upper great spines. The spines on the inferior angle are rather
smaller than those above; sides hirsute.

_Outer Maxillae_, with the inner margin slightly concave, and sparingly
covered with bristles.

_Cirri_, imperfectly preserved; the three posterior pairs have segments
of the usual character, bearing five pairs of very long spines, with the
usual little intermediate, the minute lateral, and the dorsal spines.
First cirrus lost; second and third with only their few basal segments
preserved, sufficient, however, to show that at least two or three
segments, in both the anterior and posterior rami of both cirri, were
paved with bristles.

_Pedicels_, as in the other species.

_Caudal Appendages_, lost.

This species comes very close, as far as the characters derived from the
trophi serve, to the _L. truncata_, though readily distinguished from
that species by the shape of the valves. On the other hand, the
capitulum of this species is distinguished with difficulty from that of
_L. Nicobarica_ and _L. cauta_; no doubt this difficulty is much
enhanced by the rostrum and peduncle having been lost.

5. LITHOTRYA TRUNCATA. Pl. IX, fig. 1.

ANATIFA TRUNCATA. _Quoy_ et _Gaimard_. Voyage de l'Astrolabe, Pl.
xciii, figs. 12 to 15, 1834.

_L. scutis in profundam tergorum plicam insertis: carinae crista centrali
prominente et rotundata in parte superiore: rostro et lateribus
rudimentalibus, carinae latitudinis quindecimam fere partem aequantibus._

Scuta locked into a deep fold in the terga: carina with a prominent
central rounded ridge in the upper part: rostrum and latera rudimentary,
about 1/15th of the width of the carina.

Mandibles, with nearly three times as many pectinations between the
first and second teeth, as between the second and third teeth; distance
between the tips of the first and second teeth equal to th