Galty Marine Laboratory^ St. Andrews. 9 



regions from the second segment backward, a differentiation 

 occurring anteriorly by the inflection of the groove which 

 often passes behind the tenth bristle-tuft to the mid-ventral 

 line, though in others it is further back. Each of the 

 setigerous processes anteriorly has dorsally three longer 

 Ijristles with straight shafts, tijjs bent backward, and 

 moderate wings. The edges of the wings appear to be 

 minutely serrated. Following these is a double series of 

 comparatively stout bristles, with short and broad wings, 

 making a spatulute tip with a filament in the centre. These 

 bristles also have a dorsal curve, tiie filament trending in. 

 that direction, so that they would brush an opposing 

 structure Avith the convex surface. From the nature of the 

 parts, the shafts are somewhat abruptly tapered at the tip. 

 Some of the bristles have modified tips, so that they resemble 

 a short and broad knife-blade, as in certain forms in 

 Cha;loj)te7'us, the shaft not being contiuued along the centre 

 as in the ordinary ringed types. 



In the posterior segments the bristles alter, being shorter, 

 fewer in number, and with modified tips, which have 

 moderately wide wings at the base, but they soon dimiuisli, 

 and the long central tapering tip projects far beyond them — 

 thus performing the functions of the simple bristles of this 

 region in other forms. 



The anterior rows of hooks are below the setigerous 

 processes, and consist of a long series of avicular forms, 

 M'ith serrated rows sloping to the sharp main fang, a rather 

 long, slightly striated neck with straight sides, the anterior 

 outline curving forward into the rounded prow and the 

 posterior into the well-marked basal process. Accompanying 

 each is a broad bristle, the shaft of which has a curvature 

 toward the distal end, and the tip has a region with 

 shoit wings so modified as to resemble a hook with a 

 long slia!t and a main fang. Two forms of accompanying 

 bristles thus are present in this species, viz., those with 

 broadly spatulate tips and tliose with a slightly enlarged 

 posterior curve and a beak-like point anteriorly, nearly at 

 right angles to the shaft. In a small example from Perelle 

 Bay, the latter was large and with distinct wings. The 

 hook has a larger space between the main fang and the 

 prow than in Sabella penicillus. 



The hooks behind the foregoing region are above the 

 setigerous processes, and they become fewer and fewer, as 

 well as smaller and with a longer base, in their progress 

 toward the tail. 



The tube is formed of a tough hornv secretion of an olive 



