88 SUPPLEMENT , 



side of the belly which is flatted ; the sides of the body are 

 bristled with a great number of stiff setae, long, thick, espe- 

 cially in the middle, of no great lustre, and whitish, forming 

 two longitudinal distant ranges, each ring supporting two of 

 these setae at each side. A singularity which they present is, 

 that they are all turned forwards, contrary to their arrange- 

 ment in all the other annelida ; the setae of the rings which 

 compose the anterior extremity are very large, crowded against 

 each other horizontally, so as to imitate on each side a sort of 

 comb, directed forwards, as in M. Lamarck's division of am- 

 phitrite (pectinaria), and furnished at its root with a consi- 

 derable quantity of tentacular cirri, extremely short and labial ; 

 between these two fasciculi, and at the inferior face, is the 

 head, properly so called, of a conical form, adherent to the 

 body by the summit of the cone, and elongated anteriorly into 

 a small proboscis ; it is at the base of this elongation that the 

 first buccal orifice is placed, which is continued in a sort of 

 gutter for its whole length, and which M. Otto considers to 

 ser^^e as a sucker ; the second mouth is farther back ; it is 

 much larger, and surrounded by a labial pad, in the form of a 

 horse-shoe, at the posterior part of which is a pair of tenta- 

 cula, sub-compressed, mobile, sub-articulate, and with a deep 

 furrow on the edge ; the anus is rounded, large, and altogether 

 terminal. No other orifice has been observed on the exterior 

 of this animal. 



The cutaneous envelope, rather thin, and transparent enough 

 to let the nervous and vascular system be seen through it, is 

 formed of two laminae, one of which is the skin, properly so 

 called, and the other, which M. Otto names the peritoneum, 

 still thinner, is very little adherent ; the latter, at the anterior 

 third of the body, separates the anterior cavity into two very 

 unequal parts, by a sort of diaphragm, pierced only by the in- 

 testine ; it is in the anterior part that lie the principal viscera. 

 The two mouths have each an oesophagus, about an inch long. 



