HABMOTHOE SETOSISSIMA. 347 



the typical foot (Plate XXX, fig. 12) is soon reached, showing a ventral division 

 terminating superiorly in a long conical process above the spine. The dorsal bristles 

 (Plate XL, fig. 5) spring from an oblique eminence, and are characterised by their great 

 proportional length, slight curvature, and gently tapered extremities, those next the 

 body having somewhat blunt tips, those next the ventral being more acute. The tips of 

 the blunt forms scarcely show a bare portion, the rows of spines being continued to the 

 tip, but the acute bristles next the ventral have a minute bare portion which sometimes 

 presents a slight keel. The spines are short and the rows very close, so that the bristle 

 is at once distinguished from that of Harmothoe imbricata, irrespective of the length of 

 the tip. The ventral bristles are numerous, long, and slender, the spinous region of the 

 upper forms being of great length, the rows closely arranged, and the spines rather 

 short. The tips are bifid, the terminal hook is small, and the secondary process makes 

 a very slight angle. Moreover the smooth region is remarkably short, the spines 

 passing up to the fork (Plate XL, fig. 6). Both sets of bristles are of a lustrous pale 

 yellow, almost like those of Ghloeia, and thus afford a contrast with the dull straw- 

 coloured organs of Harmothoe imbricata. In shape the ventral lobe of the foot is 

 peculiarly pointed, the base being bevelled superiorly, and with a projecting fold 

 inferiorly. 



In the terminal feet the dorsal bristles are few in number, more slender and 

 elongate, the tip pointed, and the rows of spines distinctly wider. The ventral are also 

 few in number, slender, with long, tapering, spinous regions, and attenuate, simple tips. 



The dorsal cirri present scarcely any enlargement below the filiform tip, are pale 

 throughout, have short clavate cilia sparsely scattered over the surface, and they are 

 longer distally than proximally. The ventral cirri are long subulate organs, the tip 

 extending considerably beyond the bases of the bristles. 



The dorsal bristles are the seat in some of a peculiar blackish fungoid growth, as 

 indicated in the coloured figure. This minutely granular structure finds a suitable site on 

 the spiny ridges of the dorsal bristles, and thus both shaft and tip are barred with 

 black in a characteristic manner. This coating can readily be removed by pressure, and 

 no evident change is apparent in the bristle. It is rendered brown by hydrochloric acid, 

 while caustic potash does not seem to alter it much. This growth also affects the 

 spinous region of a few of the ventral bristles. 



Habits. — This is another example of the fact that species which frequent off-shore 

 waters in the north are found between tide-marks in the south, as in the Channel 

 Islands. It is a comparatively hardy form, and the example from which the coloured 

 drawing was made lived for weeks in the centre of Perthshire, though towards the 

 termination of the period many of the ventral bristles were shed. 



After careful consideration this form has been associated with Savigny's Pohjnoe 

 setosissima. 



Audouin and Milne Edwards (1843) assigned forty segments to this species, and 

 they and Savigny found their examples at Havre. 



De Quatrefages (1865) included it under his fourth group, in which the body is more 

 or less elongated, and covered by fifteen pairs of scales. He describes the species as 

 provided with a simple triangular head; the median antenna large, about as long as the 



