ON ANNELIDA. 
79 
largement. The anus is altogether terminal, and very 
small. 
The manners and habits of the serpulse are extremely 
simple. Constantly fixed by their tube on bodies submerged 
in the sea, at tolerably great depths, all their movements are 
confined to advancing more or less out of their tube, so as to 
push forward the thorax, but rarely beyond that, and the 
gills more especially, which they develope like a fan, and 
agitate here and there. This partial sally from the tube, is 
doubtless performed by means of the hooked appendages, 
which are directed hindwards, taking their resting point on 
the parietes of the testa, somewhat in the manner that chimney- 
sweepers mount up our chimneys. On the least danger, which 
is indicated by the more rapid motion of the water, the 
animal sinks into its tube, deeply enough for its tentaculum, 
when dilated, completely to close the aperture, and thus serve 
as an operculum. We know but little concerning the sort of 
food used by the serpuloe, and still less concerning their mode 
of reproduction. It is said, however, that they are nourished 
by aquatic animalculae, which they seize by the help of their 
branchial tentacula. The origin of the tube in a part which 
is open obliquely, leads us to suppose that the young animal 
is altogether naked, and that it forms no calcareous envelope, 
until some time after its birth. 
It is known that species of this genus exist in all seas. 
Nevertheless it would be difficult enough positively to ascer- 
tain their geographical distribution, because it is possible that 
they might be confounded with the vermeti, or other animals 
with tubes. We find, however, from the researches of M. 
Savigny, on the species of this genus, — the only examination 
in which attention has been given both to the animal and 
the shell — that there are serpula) in all our seas, in those of 
India, and in those of America, and that the largest come 
from the seas of warmer climates. 
