, quadrant-shaped, with a deep square notch
cut out of the arched margin, which notch receives the upper point of
the carinal latera; the surface of the valve between the notch and the
umbo is depressed.[56]

_Rostral Latera_, small, gradually widening from the umbo to the
opposite end, which is obliquely rounded.

_Infra-median Latera_, approaching to diamond-shaped, placed obliquely
to the longer axis of the capitulum; or the upper part may be described
as spear-shaped.

[56] The only valve which I have seen at all like this, is a
fossil specimen from the Upper Chalk of Scania; this is described
in my memoir on the Fossil Lepadidae (Palaeontographical Society),
under the name of _Scalpellum solidulum_ (Tab. 1, fig. 8, _e_,
_f_), and is perhaps erroneously there considered as a carinal
latus.

_Carinal Latera_: these appear as if formed of two valves united
together; the upper portion, widening as it ascends in a curved line,
terminates in a rounded margin, which enters the deep notch in the upper
latera; the other and lower portion is shorter, and terminates in a
square margin abutting against the infra-median latera; the umbones of
the carinal latera project beyond the line of the carina.

_Direction of the Lines of Growth in the Valves._--This should always be
carefully observed, on account of the great diversity there is in this
respect between the different species, especially when the recent are
compared with the older fossil species; moreover one of the chief
characters between the genus Scalpellum and Pollicipes, depends on the
direction of the lines of growth. In the scuta, terga, rostrum, and
upper latera of the present species, the chief growth is downwards; in
the carina, in mature specimens, it is both upwards and downwards; in
the carinal latera, both upwards and towards the infra-median latera; in
the infra-median latera chiefly upwards; and, lastly, in the rostral
latera, towards the infra-median latera.

_Peduncle_, short, not half as long as the capitulum; calcareous scales
imbricated as usual, tinged red, almost crescent-shaped, acuminated at
both ends, of remarkable length, so that in each whorl there are only
four scales: a full-sized scale equals in length one of the rostral
latera. The tips of two scales, in one whorl, lie under the middle
points of the carina and rostrum; and in the whorl, both above and
below, a single much curved scale occupies this same medial positio