388 HALOSYDNA GELATINOSA. 



with the dorsal margin of the foot. The bristles are somewhat stronger and the spinous 

 regions shorter. The tips of the upper series are less acute, and those of the stouter 

 inferior show traces of the expansion. The backward curve of the lower series is 

 marked. The ventral cirrus reaches only to the tip of the adjoining fleshy part of the 

 foot. 



In the next (fourth) foot a slight elevation internal to the long sheath for the spine 

 exists, as an indication of the dorsal division. The tips of the ventral bristles are now 

 shorter and wider. 



In the typical foot (Plate XXX, fig. 11) the dorsal division forms a small process 

 on the upper and anterior border, and is best seen in the elytrophorous feet, since the 

 enlarged base of the dorsal cirrus in the others obscures it. The inconspicuous tuft 

 consists of slender translucent bristles with faint serrations, and tapering to a fine point 

 (Plate XLI, fig. 1). The bristles of the ventral series are comparatively slender and 

 translucent, while the tips are flattened out in varying degrees. The superior series 

 (Plate XLI, fig. 2) have elongated spinous regions, and simple, slightly blunt tips ; while 

 the broader middle series (Plate XLI, fig. 3) have a strong curved hook at the tip, with 

 a secondary process immediately beneath. The flattened spinous region is marked by 

 the oblique lines from the rows of spines as in Malmgrenia. Langerhans specially refers 

 to the changes in the bifid tip of the ventral bristles. The ventral cirrus does not now 

 reach the tip of the fleshy part of the foot. 



Posteriorly the bristles become extremely slender, with a capillary tip. The ventral, 

 however, retain a trace of the enlargement at the base of the spinous region. The 

 bristles on the last foot are stout. The ventral cirrus extends almost as far as the tip of 

 the inferior division of the foot. 



Parasites on the bristles are rare. 



The dorsal cirri are rather long, slender organs, with a filiform tip, and a dark belt 

 at the slight swelling immediately below. Their surface is smooth. A considerable 

 nerve passes up the centre of the organ nearly to the tip, giving off' branches as it 

 proceeds. 



Habits. — This species is fond of clinging to the under surface of stones in pools near 

 low-water mark, from the north of Scotland to the Channel Islands, and no marked 

 difference in size is found on contrasting specimens from the extremes. In Bressay 

 Sound it is very abundant in old bivalve shells, in crevices in the "roots" of the 

 tangles, and on the surfaces of the valves of the " horse "-mussels bound together by 

 the foregoing " roots." Sir J. Dalyell many years previously procured it from this 

 region — under shells. He gives an interesting account of the rapacity of one in con- 

 finement which devoured its fellow, the teeth of the proboscis audibly striking the 

 glass as it darted it out to conclude its meal. In various Polynoida3 this tapping on 

 the glass occurs occasionally in confinement. Fishes seem to find it out readily in 

 deep water, for large examples are frequent at St. Andrews in the stomach of the cod 

 and haddock. 



It is active and irritable, and frequently ruptures its body if held by the middle, or 

 when put in spirit. Sir J. Dalyell found it timid and nocturnal, yet watchful for prey. 



Reproduction. — Eipe males occur at St. Andrews towards the end of November. A 



