TEREBELLTDES STROEMI. . 213 



then the succeeding belts are narrow, separated by increasing breadths of non-glandular 

 tissue. Further, an almond-shaped area beneath each setigerous process is differentiated, 

 and on this the hooks appear on the sixth bristled segment and thereafter it becomes the 

 uncinigerous process, whilst between each a lateral glandular belt is continued 

 backward behind the bristled region on each side to the tail. 



The general colour of the body is reddish or pale orange anteriorly, marked with red 

 laterally. Posteriorly it is greyish yellow (from the grey mud in the intestine). The 

 snout is pale, the branchiae are of a deeper red or have pinkish lamella, and a red 

 blood-vessel. 



In this form the dissepiments are only developed posteriorly (Hessle). 



The first setigerous process commences on the second segment, at the upper or 

 lateral edge of the ventral glandular belt, and below it is a slightly curved elevation with 

 the convexity anterior. Seventeen setigerous processes follow. Each is short and stout, 

 with a slightly bevelled tip grooved for the bristles. The first and second are smaller 

 and they slightly diminish posteriorly. The pale golden bristles (Plate CXXVII, figs. 5, 

 5' and 5") have long and nearly cylindrical shafts, a little narrowed at the proximal end,, 

 and distally tapering to a somewhat stiff curved tip, which ends in a hair-like point. 

 The tip has narrow but distinct wings. The bristles appear to be in a single series, the 

 stouter dorsal and the more translucent and slender ventral in position. Some present 

 a stout shaft finely striated, and a peculiar and rather abrupt curvature at the tip 

 (Plate CXXVII, fig. 5"), and apparently have a special function. 



The rows of hooks commence on the sixth segment and continue to the posterior 

 end. In the bristled segments anteriorly they occur on slightly elevated ridges a short 

 distance below the setigerous processes with the exception of the first, which is close to 

 the base of the process. The ridges become more prominent before the bristles cease. 

 The rows are often conspicuous from their brownish colour. The golden hooks of the 

 first row not only diverge in position but in structure, for they are larger and 

 longer, have translucent shafts which dilate a little above the base, and again gradually 

 diminish to the neck, which is curved backward, the tip being bent at a little more than 

 a right angle and tapered to a sharp point — slightly turned up in some. The second 

 series shows hooks of the normal outline, besides others imperfectly formed — with 

 shorter shafts, and slightly curved, bifid tips, a distal longer and another shorter process 

 at a distance below it. The typical hook (Plate CXXVII, fig. 5 a) has a long, slightly 

 curved, finely- striated shaft which is slender at the base, dilates gradually in its 

 progress to the shoulder, near which it diminishes, the neck then being bent a little 

 backward, the enlarged crown having four teeth above the main fang, which is powerful 

 and sharp. 



The uncinigerous processes become more prominent behind the bristled region, on 

 slightly flattened lamellae with wider truncated tips, and attain their maximum about the 

 twentieth from the end, and gradually diminish backward. In this region the hooks are 

 all of one kind and essentially different from those in the anterior region. Each hook 

 (Plate CXXVII, fig. 5 b) has a convex posterior region with a deep dimple above the 

 base, three large teeth above the main fang, the anterior outline having a slight process 

 below the main fang, whilst the base is convex inferiorly and short, the somewhat 



