ongitudinal row; dorsal
tufts, with four or five long spines. The second cirrus has its anterior
ramus not thicker, but rather shorter than the posterior ramus; the
former is only a little more thickly clothed with spines, owing to those
in the longitudinal lateral row being longer and more numerous, than is
the sixth pair of cirri. Bristles not serrated.

_Caudal Appendages_, narrow, thin, slightly curved, about half as long
as the pedicels of the sixth cirrus; in young specimens, the appendage
bore seven or eight pair of long bristles rectangularly projecting; in
some older specimens, there was a tuft of bristles on the summit, and
two other tufts on the sides.

I at first thought that the Borneo specimen was a distinct species, but
after careful comparison of the external and internal parts, the only
difference which I can detect is, that the terga are slightly larger,
and that the carina, to a more evident degree, is wider, more especially
in the middle and lower portions.

2. DICHELASPIS GRAYII. Pl. II, fig. 9.

_D. scutorum segmento basali angustiore quam segmentum occludens;
longitudine paene dimidia: tergis bipenniformibus, margine crenato, spina
postica, manubrio angustiore quam occludens scutorum segmentum._

Scuta, with the basal segment narrower than the occludent segment, and
about half as long as it. Terga like a battle-axe, with the edge
crenated and a spike behind; the handle narrower than the occludent
segment of the scuta.

Mandibles with three teeth; cirri unknown.

Attached to the skin of a sea-snake, believed to have been the
_Hydeus_ or _Pelamis bicolor_, and therefore from the Tropical,
Indian or Pacific Oceans; associated with the _Conchoderma
Hunteri_; single specimen, in a very bad condition, in the Royal
College of Surgeons.

_General Appearance._--Capitulum much compressed, elongated, formed of
very thin membrane, with the valves forming round it a mere border.
Valves thin, imperfectly calcified, covered with membrane.

_Scuta_ formed of two narrow plates at very nearly right-angles to each
other, one extending along the occludent, and the other along the basal
margin; both become very narrow at the point of junction, and are there
not calcified, but are evidently continuous and form part of the same
valve; the basal segment is about half as long and narrower than the
occludent segment, flat and bluntly pointed at the end; occludent
segment slightly curled, an