180 Notes from the Oatty Marine Laboratory* 



in S. spinulosa. The ventral surface has a deep median groove, 

 commencing with the first segment of the region and con- 

 tinuing to the last, for the reception of the caudal tube 

 as it curves to this surface. Two transverse ridges cross 

 the groove in front of the anterior area, the second being 

 slightly bent forward, and the next (third) curved more 

 boldly backward to suit the ovoid boss. As with the grooves 

 on the dorsum, these transverse ridges are opposite the 

 middle of each segment. 



This region (second body-region) has no dorsal bristles. 

 A ridge passes from each branchia laterally and ventrally, 

 almost to the edge of the ventral groove. The upper third 

 of the ridge is flat, then the torus for the uncini project and 

 end ventrally in a papilla; lastly, the ridge is continued ven- 

 trally and ends in a process for the ventral bristle-tuft and 

 a small subulate cirrus external to or behind it. The first 

 has the longest and largest cirrus, and it is situated to the 

 exterior of the bristle-tuft, and the next five or six, though 

 less, are easily seen to the exterior of the bristles. By-and-by, 

 in their progress backward, they diminish and fall to the 

 rear of the bristle-tuft, and in the caudal region they form 

 only flattened eminences behind the tufts. The first torus 

 for the hooks is of great length, and so with the second, but 

 the others gradually diminish, the last eight or nine being 

 cirriform. The hooks are similar to those of S. spinulosa, 

 presenting six teeth in lateral view, the basal end, however, is 

 somewhat more truncate distally. Front views show at least 

 a double series of teeth along the edge. Each has its distal 

 and two proximal tendons, and the numbers are great, the 

 tendons forming an asbestos-like mass of fibres in each case. 

 The posterior hooks are smaller, but do not differ materially 

 in outline. 



The first bristle-tuft of the region is directed horizontally 

 inward, and in structure it possesses intermediate characters, 

 having about six or seven strong golden bristles with long 

 flattened oar-shaped tips and elongated points, the surface of 

 the tip being minutely spinous. There are, besides, about 

 the same number of forms with more slender shafts and finely 

 tapered tips, densely covered with minute whorls of spikes. 



The second ventral tuft of pale golden bristles is directed 

 inward and slightly forward, but it conforms to the ventral 

 type of structure, some of the bristles having stouter longi- 

 tudinally striated shafts, others more slender, but all having 

 slender tapering tips clothed with whorls of spikes directed 

 distally. The rest of the bristles of the region have their 

 tips directed forward and inward, those in the caudal region 



