104 
SUPPLEMENT 
lias a strong lateral muscle, which is carried from the lateral 
base to the side of the general muscular sheath ; another, 
more considerable, belongs to the second cephalic ring: it 
attaches itself to the lateral face of this ring, and is elon- 
gated pretty far backwards into the visceral cavity, be- 
tween the intestinal canal and the longitudinal cutaneous 
stratum ; one or two small oblique fasciculi, and much 
shorter, proceed from the first cervical to the posterior cephalic 
ring. The buccal mass, or mouth, with its appendages, is 
drawn back by a very powerful muscle, which is inserted 
at its dorsal and lateral face. What is more remarkable is, 
that the enlargements of the intestinal canal, at least the ante- 
rior ones, have also retractor muscles ; those which carry the 
buccal mass forward, are altogether dorsal, and much less 
strong : the teeth are as it were implanted by a sort of pedi- 
cle, in the very parietes of the oesophagus, or rather of the 
buccal cavity, the fibres of which are longitudinal; and they 
are surrounded from their base to a little distance from their 
far extremity, by a thick stratum of transverse fibres, which 
must act in the manner of a powerful sphincter. 
The mouth of the nereides, in the species provided with a 
true proboscis, and even in those which have one formed by 
proboscidian rings, is always terminal, and consisting of a 
rounded orifice, and sometimes of a transverse cleft ; but in 
the multidentated species, it is a sort of oblique cleft under- 
neath and behind the first ring. 
The proboscis, properly so called, may be considered as a 
very long ring, sometimes filiform, and at other times more or 
less claviform, and enlarged at its extremity. The skin 
which invests it is always much thinner than on the rest of the 
body ; in fact, this organ is often retracted into the interior 
part of the intestinal canal, pretty nearly like the tentacula of 
the limacinse. It is rarely armed at its extremity ; sometimes, 
however, there are two pairs of little hooks, one at each cor- 
