tremely long, as are
the pedicels; the segments are much elongated, with their anterior faces
not at all protuberant; each bears five pair of very long and thin
spines, with an excessively minute one between each pair; the dorsal
tuft consists of very fine and thin spines. The second cirrus has its
anterior ramus not at all thicker than the posterior ramus; but has an
exterior third longitudinal row of small bristles. First cirrus,
separated by a wide interval from the second pair; very short with the
two rami slightly unequal in length; the segments are broad, and are
paved moderately thickly with spines; the terminal spines not
particularly thick.

_Caudal Appendages_ consist of very small and narrow plates, about half
the length of the pedicels of the sixth cirrus, with a few long spines
at their ends.

This well-marked species, I think, has not more affinity to one than to
another of the previous species: it differs from all, in the junction
between the two segments of the scuta being perfectly calcified; in the
peculiar cup, forming the base of the carina; and lastly, in the
inferior part of the maxillae projecting.

OXYNASPIS.[33] _Gen. Nov._ Pl. III.

_Valvae 5, approximatae: scutorum umbones in medio marginis occludentis
positi: carina rectangule flexa, sursum inter terga extensa, termino
basali simpliciter concavo._

Valves 5, approximate; scuta with their umbones in the middle of the
occludent margin; carina rectangularly bent, extending up between the
terga, with the basal end simply concave.

[33] From [Greek: oxuno], to sharpen, and [Greek: aspis], a
shield or scutum.

Mandibles with four teeth; maxillae notched, with the lower part of edge
nearly straight, prominent; anterior ramus of the second cirrus thicker
than the posterior ramus; caudal appendages, uniarticulate, spinose.

Attached to horny corallines.

I have most unwillingly instituted this genus; but it will be seen by
the following description, that the one known species could not have
been introduced into Lepas or Paecilasma, without destroying these
genera, although it has a close general resemblance with both. As far as
the valves are concerned, it is more nearly related to Lepas than to
Paecilasma; but taking the entire animal, its relation is much closer to
the latter genus than to Lepas: it differs from both these genera in the
manner of growth of the scuta, which is both upwards and downwards, the
primordial valve b