418 DR W. CARMICHAEL M'lNTOSH ON THE STRUCTURE OF THE 



head is of an acutely conical form, with two distinct eye-specks at its posterior 

 border, close to the first transverse sulcus. Its body is much more slender than 

 that of L.fragilis, and at once attracts notice by its characteristically marked 

 segments, which, with the exception of a few anteriorly, assume quite a monili- 

 forin appearance. In the structure of its feet it differs from all the foregoing 

 species. Each foot is furnished with a small branchial lobe (Plate XVI. fig. 17 a) 

 in which a single vascular loop is observed ; and thus it would appear to fall 

 under the genus Notocirrus, Schmarda,* though the possession of the eyes is 

 exceptional. The tip of a stout spine or two (b) projects beyond the foot amongst 

 the bristles. The latter (c) have simple shafts with a broad spear-tip, which 

 tapers to a fine point, and is faintly serrated along part of the edge. 



Hpalincecia sicula, Qtjatref. (?) — This is a small representative of the Onu- 

 phididce, dredged in 90 fathoms off North Unst, Shetland, by Mr Gwyn Jeffreys, 

 F.R.S. It is characterised in spirit by two parallel bands of brown which course 

 along the lustrous dorsum from a transverse belt of the same colour immediately 

 behind the head, and by a brown spot between each foot from the fifth backwards. 

 There are three elongated tentacula (a median and two lateral), and two shorter 

 in front, as in H. tubicola, Mull. The small black eyes are situated at the outer 

 side of the base of the long lateral. All the tentacles have a crenated base. The 

 antennae are similar to those of H. tubicola, or perhaps slightly longer. In the 

 structure of the bristles of the anterior feet, however, a very diagnostic feature 

 occurs ; for instead of the large unjointed winged hooks, which are found in the 

 latter and in Nothria conchilega, Sars, there are peculiar jointed structures (Plate 

 XVI. fig. 3); and the bristles (fig. 3 c) are slender, and furnished with a very 

 narrow wing, whereas in both of the other species they are shaped like a Valentin's 

 knife. Posteriorly the jointed hooks are supplanted by two simple ones (fig. 3 b), 

 which are stouter and slightly curved. Some of these occasionally present no 

 wing at the tip. The bristles in this region are also shorter, and some are 

 characteristically curved at the point. None of the peculiar brush-shaped bristles 

 common in the two species above-mentioned occurred in this animal. No tube 

 accompanied it ; but I have since found that this species inhabits a tube com- 

 posed of gravel and shell-fragments, and thus differs very considerably in its 

 habitation from H. tubicola, while the length and form of the tube also distinguish 

 it at once from that of Nothria concJnlega. The foregoing animal has certain close 

 affinities with the Onuphis sicula of M. be Quatrefages,| but differs from the 

 description of that author in so far as the bases of the tentacles do not occupy the 

 whole surface of the head, which in the Sicilian species is very small. The body 

 is rounded in the latter, flattened in the British ; and the bristles of the former 

 are said by M. de Quatrefages to present a great resemblance to those of 



* Neue wirb. Thiere, &c. torn. i. ii. p. 114. f Anneles, vol. i. p. 352. 



