332 MR. A. HANCOCK ON A BURROWING BARNACLE 
transverse plates or hairs which taper towards their points, and 
are stout at their origin, where they are slightly bifid, and exhibit 
for some distance upwards, the appearance of two channels. There 
can be little doubt that these organs are for branchial purposes. 
The chamber in which the animal is lodged, is partially lined 
with calcareous matter secreted by the tenant ; this lining is very 
thin, and principally confined to the side walls of that part in 
which the anterior portion of the animal is lodged: here the 
lining gradually thickens as it approaches the margins of the slit, 
and passes a little beyond them, particularly towards its poste- 
rior termination. On looking down upon the slit, this shelly 
lining is seen distinctly projecting inwards from the margins, and 
exhibiting two or three longitudinal ridges marking periods of 
‘growth, narrowing the opening backwards as the increase of the 
animal requires the advancement of the aperture in front. Shelly 
granules may also occasionally be seen filling up the curved pos- 
terior extremity of the slit. 
Notwithstanding the abundance of this animal, I have not yet 
been able to investigate the internal anatomy, many specimens 
having necessarily been destroyed in making the external exami- 
nations, and others suffered in attempts to remove them from 
their abode. This important part of the description must there- 
fore for the present, be left almost untouched. 
The cloak below is free for a considerable way backwards ; 
above, immediately behind the slit, it is united in front with the 
true body of the animal, and behind, where the broad disc-like 
expansion is covered with the horny plate, it blends with a 
thickish layer of parenchymatous matter. The stomach is long 
and narrow, and passing downwards and backwards from the 
mouth, bends rather suddenly forwards, and gradually tapering 
is continued into the cylindrical, fleshy pedicle which supports 
the arms, near to which it probably terminates. No caudal 
prolongation of this part was observed similar to that which is 
common to all the other Cirripedes; the generative organs are 
therefore probably modified in this animal. 
Adhering to the parenchymatous matter, beneath the horny 
plate, the eggs are found spread out into a leaf-like expansion 
