er than the others,) a
rostrum, sub-rostrum, sub-carina, and three pair of small latera. All
the valves are covered by membrane, as are the calcareous scales on the
peduncle; and this membrane everywhere is densely clothed with spines.
The upper valves are not very thick; they stand rather close together.
The eight valves of the lower whorl are more solid, and are placed far
apart; they are small, tending to become rudimentary. None of the valves
are added to at their upper ends, in which respect this species differs
remarkably from the others of the genus, and approaches in character to
Pollicipes.

_Scuta_, with a deep hollow for the adductor muscle, triangular, with
the basal margin elongated, and protuberant.

_Terga_, large, flat, triangular, basal point blunt, with the carinal
margin slightly hollowed out, and the scutal margin protuberant. Apex
solid.

_Carina_, rather longer than the terga, straight, gradually widening
from the upper to the basal end, deeply concave. In young specimens the
upper part is slightly bowed inwards. Apex solid.

_Sub-carina_, with the inner surface crescent-shaped; the umbo points
transversely outwards; in width it exceeds the largest of the latera.

_Rostrum_, triangular, internally (fig. 8 _a_) concave; basal margin
slightly hollowed out, and deeply notched; rather less in width than the
carina; short, with the umbo pointing upwards and outwards. In young
specimens the apex curves a little inwards.

_Sub-rostrum_, with the inner surface transversely elongated (fig. 8
_b_), slightly crescent-shaped, about two thirds as wide as the rostrum.
The apex points transversely outwards.

_Latera_, three pair; the middle pair apparently corresponds with the
upper latera of the other species of the genus. The two other pair of
latera, together with the rostrum and sub-carina, form a whorl. The
sub-rostrum lies by itself, a little beneath this whorl. The latera are
smaller than the rostrum or the sub-carina. They are placed far distant
from each other; their inner surfaces are triangular; their umbones
point upwards; the rostral pair is smaller than the other two pair,
which are of equal size. The exact position of the rostral latus
differed on the two sides of the specimen examined; apparently its
normal position is at the baso-lateral angle of the scuta.

_Peduncle_, wide at the summit, longer than the capitulum; calcified
scales small, not arranged very regularly; flattened, spindle-