Psamathe fusca. 



15 



to me, between Scyllis and Hesion*. It differs from the first 

 in the number and structure of the tentacula, in the form of 

 the head, and in the arrangement of the eyes ; and from the 

 latter in the form of the body, which, I think, is a very impor- 

 tant character, and in the structure of the proboscis, which, in 

 Hesion^, is very long and destitute of oral papillae. I have 

 seen but one species which may be named. 



51. Psa'math£ fu'sca. (j%. 1.) 



a, PsSmathe fusca, considerably magnified ; b, the head, with the proboscis protruded, more 

 highly magnified ; c, a foot, very much enlarged j rf, a bristle ; e, a spine. 



Description. — Animal scolopendriform, 1 inch long, slightly 

 narrowed at the head, tapered towards the tail, constricted 

 between the segments, of a yellowish-brown or fuscous co- 

 lour : head small, square, entire in front ; eyes 4, very dis- 

 tinct, occipital, placed in pairs ; tentacula 4, very short, un- 

 jointed, frontal, the superior pair thicker than the inferior; 

 mouth terminal, edentulous, furnished with a very short 

 thick proboscis, whose aperture is encircled with a double 

 series of papillae ; tentacular cirri 4 pairs on each side, the 

 inferior about half the length of the superior, jointed, and 

 issuing from a bulged base; segments numerous, nearly of 

 the same breadth and length ; feet much developed and very 

 prominent, all alike, conic, the apex divided into two obtuse 

 lobes between which the bristles are protruded : on the upper 

 side of the foot there is a long cirrus, jointed like a Conferva, 

 scarcely moniliform, and arising from a swollen basilar 

 sheath ; on the ventral aspect the cirrus is short, not extend- 



