n Professor Bell's work on the British
Crustacea, it will be found that each species retains the same
characters in greater or less degree.

_Galathea strigosa_ is peculiar for the spinous character of the
carapace and cheliform legs. Every spine, however, is repeated in both
the other species, only less developed. We find the rostrum furnished
with four lateral teeth on each side, a character which also exists in
each of the other species; and although close observation may detect a
slightly different arrangement in the relative position of these teeth,
the differences are not of sufficient importance to enable a naturalist
thence to derive a specific distinction, unless the peculiarity is
seconded by some more unqualified character less liable to be affected
by any peculiarity of condition.

In order to arrive at more certain results in the identification of
species, we think that the microscopic examination of the surface of the
integument will be found peculiarly useful.

This mode of examination of species may also be applied to a
considerable extent throughout the Crustacea generally with great
advantage; and if found valuable in recent, there can be no doubt that
it will prove of far greater importance in extinct forms, where parts
on which the identification of species visually rests are lost, and
fragments only of the animal obtainable.

It should be borne in mind that, as the structure in question undergoes
modifications more or less considerable in different parts of the
animal, it will always be advisable to compare the corresponding parts
with each other.

Applying this test to the known species of _Galathea,_ we perceive that
the structure of the integument upon the arms, independent of the
marginal spines, exhibits a squamiform appearance, but that the scales,
which characterise the structure, possess features peculiar to each
species.

In _Galathea strigosa_ the scales are convex, distant from each other,
smooth at the edge, and fringed with long hairs. In _G. squamifera_ they
are convex, closely placed, scalloped at the edge, and without hairs. In
_G. nexa_ the scales are obsolete, tufts of hair representing the
supposed edges. In _G. depressa_, n. sp., the scales are broad, less
convex than in _G. strigosa_ and _G. squamifera_, smooth, closely set,
and fringed with short hairs. In _G. Andrewsii_ they are small, distant,
very convex, tipped with red, and slightly furnished with hair.

As anothe