193 
VERMETUS. Lamarck , Hist . Nat. 
( Vermicularia , supra vol. i. p. 125.) 
Gen. Char.* Shell tubular,, in part spiral, fixed by 
its apex ; operculum corneous, flat, attached 
to the foot of the cephalous animal. 
It is by the animal principally that the Vermetus (for- 
merly called Vermicularia by Lamarck) is distinguished 
from Serpula and similar genera : it is formed by an ani- 
mal not composed of joints, that has a distinct head, two 
tentaculae, with an eye at the base of each, and a cylindri- 
cal foot (or analogous part) supporting a horny operculum, 
and consequently nearly related to the animals of true 
spiral shells, and belonging to Trachelepodous mollusca. 
There does not appear to be any certain external cha- 
racter to distinguish the shell by ; but the animal seems 
much less disposed to attach any large portion of its shell 
to foreign substances, and generally forms a tolerably re- 
gular and more or less open spire of the commencement 
of its tube, which is either discoid or conical. There can 
of course be no certainty respecting the fossil species; 
but as it is convenient to separate those shelly tubes which 
have hitherto been called Vermiculariae, from among the 
Serpulae, we shall still consider such as have been attach- 
ed only by the apex (which, by the bye, form a very na- 
tural group) as belonging to the genus Vermetus. Most 
of the individuals turn one way, which, if the cone be 
placed in the same position, is found to be the reverse of 
most univalves. 
* The generic character formerly given being inaccurate, and 
the observations upon it being founded partly in error, we wish 
to cancel them. 
