concave within;
lower end triangular, abruptly truncated, and not crested.

_Primordial valves_ very plain, with the usual hexagonal structure:
those of the terga, rounded at both ends, instead of being square, as in
the mature calcified valves.

_Peduncle_ short, narrow, not half as long as the capitulum; paved with
minute equal beads, as in the genus Dichelaspis.

_Mouth._--Mandibles with the fourth tooth very small; inferior angle
rudimentary. Maxillae, with three great upper spines, beneath which there
is a deep notch bearing some delicate spines; inferior upraised part, as
in _P. Kaempferi_.

_Cirri._--Rami of first cirrus hardly more than one third as long as the
rami of the second cirrus, which latter rami are unequal in length by
only two segments; the posterior ramus being the longer one.

_Caudal Appendages_, with only two or three lateral bristles, besides
those on the summit.

_Size._--Capitulum, three to four tenths of an inch long.

_General Remarks._--This species has the closest general resemblance to
_P. Kaempferi_, and is evidently a representative of it. On close
examination, however, almost every part differs slightly; the chief
points being the narrowness of the basal margin of the scuta; the
obliqueness of the truncated basal end of the terga and the sharpness of
the upper end; the rudimentary state of the inferior angle of the
mandibles; the character of the spines on the maxillae; the proportional
lengths of the cirri, and the fewness of the spines on the outer sides
of the caudal appendages. The fact of Madeira having this Paecilasma, a
representative both in structure and habits of a Japan species, is
interesting, inasmuch, as I am informed by Mr. Lowe, that some of the
Madeira fishes are analogues of those of Japan.

3. PAECILASMA CRASSA. Pl. II. Fig. 3.

ANATIFA CRASSA. _J. E. Gray._ Proc. Zoolog. Soc., 1848, p. 44,
Annulosa, Tab. iii, figs. 5, 6.

_P. valvis 5; carinae termino basali in discum parvum infossum producto:
scutis convexis, dentibus internis umbonalibus nullis: tergis paene
rudimentalibus, vix carina latioribus._

Valves 5; carina with the basal end produced into a small imbedded disc;
scuta convex, without internal umbonal teeth; terga almost rudimentary,
scarcely broader than the carina.

Spines on the segments of the posterior cirri arranged in single
transverse rows.

Madeira; attached to the _Homola Cuvierii_, Rev. R. T. Lowe.
British Mus