ON ANNELIDA. 79 



lavgement. The anus is altogether terminal, and very 

 small. 



The manners and habits of the serpula? 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 serpulaj, 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 ten taenia. 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 serpul^e in all our seas, in those of 

 India, and in those of America, and that the largest come 

 from the seas of warmer climates. 



