pecimens _just attached_, in which no absorption has taken place, two
long muscles with transverse striae may be found attached to the knobbed
tips of the two middle arms of the two = deg.UU deg.=, and running up to
the antero-dorsal surface of the carapace, where they are attached; other
muscles (without transverse striae) are attached round the bases, on both
sides of both forks. The action of these muscles would inevitably move
the eyes, but I suspect that their function may be to draw up the
narrow, deeply folded, sternal surface, and thus cause the retraction of
the great prehensile antennae within the carapace.

_Mouth._--This is seated in exactly the same position as in the mature
Cirripede, on a slight prominence, fronting the thoracic limbs, and so
far within the carapace, that it was obviously quite unfitted for the
seizure of prey; and it was equally obvious, that the limbs were
natatory, and incapable of carrying food to the mouth. This enigma was
at once explained by an examination of the mouth, which was found to be
in a rudimentary condition and absolutely closed, so that there would be
no use in prey being seized. Underneath this slightly prominent and
closed mouth, I found all the masticatory organs of a Cirripede, in an
immature condition. The state of the mouth will be at once understood,
if we suppose very fluid matter to be poured over the protuberant mouth
of a Cirripede, so as to run a little way down, in the shape of internal
crests, between the different parts, and in the shape of a short,
shrivelled, certainly closed tube, a little way (.008 of an inch in _L.
australis_) down the oesophagus. Hence, the larva in this, its last
stage, cannot eat; it may be called a _locomotive Pupa_;[11] its whole
organisation is apparently adapted for the one great end of finding a
proper site for its attachment and final metamorphosis.

[11] M. Dujardin has lately ('Comptes Rendus,' Feb. 5, 1850, as
cited in 'Annals of Nat. History,' vol. v, p. 318,) discovered
that the "Hypopi are Acari with eight feet, without either mouth
or intestine, and which, being deprived of all means of
alimentation, fix themselves at will, so as to undergo a final
metamorphosis, and they become Gamasi or Uropodi." Here, then, we
have an almost exactly analogous case. M. Dujardin asks--"Ought,
therefore, the Hypopi to be called larvae, when, under that
denomination, have hitherto been comprised animals capab