336 MR. A. HANCOCK ON A BURROWING BARNACLE 
form a prehensile net of the most efficient nature, and the only 
currents produced result from its action. 
In habit, too, this animal differs from all known Cirripedes ; 
none, I believe, but this species bury themselves in hard calca- 
reous bodies : some indeed partially conceal themselves in foreign 
substances, and all may be said, in a certain sense, to be parasi- 
tical. Z'ubicinella and Coronula are well known to sink deep into 
the skin of whales; but, in both cases, the whole of the valvular, 
or upper portion of the animal, is exposed; and as both are well 
protected by their shells, it is evident that this habit is not for 
defence, the object apparently being to avoid that resistance of 
the surrounditig element, occasioned by the rapid movements of 
this huge animal, and the consequent difficulty there would be 
in maintaining their hold of its smooth, contractile surface. 
Other genera, Prygona, Crusia and Acasta, are found concealed 
in corals and sponges ; none of them, however, excavate: these 
bodies simply grow round the Cirripede, and as it augments in 
size, which it does by increasing upwards, so does the coral or 
sponge advance withit. Lithotrya is the only genus of the class 
that has been described as actually excavating a habitation in 
hard calcareous bodies ; there is reason, however, to doubt the 
fact, as we shall see, by carefully examining Mr. Sowerby’s own 
figures in his ‘ Genera of Shells.’ This creature is a pedunculate 
Cirripede, and is stated to have at “ the base of the peduncle, a 
shelly appendage.” Forthe moment granting this to be true, it 
is evident that the holes it occupies, if made by itself, can only 
have been formed by either this appendage, or by the base of the 
pedicle before the shelly appendage was secreted. But on refer- 
ring to the figures just alluded to, it would appear that neither 
hypothesis is correct. In one of these figures, there is very cor- 
rectly delineated a couple of Serpule, adhering to the under sur- 
face of the basal appendage. Now it is pretty clear, that were 
this appendage used as a rasping surface, no Serpule could exist 
as represented ; and were the excavations effected before the for- 
mation of this appendage, it must necessarily partake of the 
shape of the base of the newly-formed chamber to which it would 
be closely adherent, as in the parallel case of Hipponya: it would 
