104 SUPPLEMENT 



has 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 suiTounded 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 limacinae. It is rarely armed at its extremity ; sometimes, 

 however, there are two pairs of little hooks, one at each cor- 



