30 SABELLARIA ALVBOLATA. 



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-b}^ 

 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 (Plate CXXIII, fig. 8 e) are 

 similar to those of 8. spimilosa, presenting six teeth in lateral view ; the basal end, however, 

 is somewhat more truncate clistally. 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 longitudinally striated shafts, others more slender, but all having slender tapering 

 tips clothed with whorls of spikes directed clistally. The rest of the bristles of the 

 region have their tips directed forward and inward, those in the caudal region being even 

 more conspicuous than those in front, and they have proportionally shorter tips and 

 longer shafts, the imbricated spikes forming a scale-like arrangement on the front of the 

 bristle, whilst the back is smooth. A more or less alternating series of stronger and 

 more slender bristles occurs in each tuft, which is antero-posteriorly spread, like a fan 

 over the soft caudal tube in its ventral groove. Arnold Watson is of opinion that the 

 function of the ventral bristles is largely connected with the passage of the waste matter 

 forward, and they keep the caudal appendage in a central position. He met with an 

 abnormality at the eighteenth abdominal foot which had an extra fascicle of bristles 

 about half the size of the ordinary one and situated internally. 



The caudal tube bends smoothly to the ventral groove, and extends more than half- 

 way forward on the ventral surface, diminishing a little as it proceeds. A purplish- 

 brown pigment patch marks its commencement. Two ridges (probably muscular) occur 

 on the ventral surface, with a median groove between them and a lateral furrow at each 

 side. The anal aperture at the tip is usually ovoid in the preparations, with the long 

 diameter transverse. 



Arnold Watson has found the intestine infested with Selenidium even in young 

 worms only 2 mm. long. In another sickly young specimen a group of parasitic 

 Nematodes (?) were waving out of the anus. 



In a very young example with two eye-specks, Arnold Watson observed two light 

 brown bodies at the junction of the caudal process with the trunk, and noticed that the 

 peristaltic action of the gut was from behind forward. He also observed glandular pores 



