Gatty Marine Laboratory , St. Andrews. 537 



ventral of the third pair forming long stiff straight bristles, 

 whilst the hooks of the fourth pair are short, broad, flattened 

 knives with a curve at the tip. This form of crotchet con- 

 tinues a short distance and passes into a series of longer, rigid, 

 lever-like spines posteriorly. 



So far as the two fragments, apparently of the same 

 animal, show, the shape is generally that of the common 

 species, the entire surface being closely villous from clavate 

 papillas, which are longest on the first three segments, and 

 especially the first, but no sand-grains are visible. The 

 general colour is a kaki-brown, and the segments are more 

 than 20 in number. The papilla? are smaller on the 

 ventral surface, and, as on the dorsum, they are more con- 

 spicuous on the anterior segments. The anterior pit for the 

 emission of the oral organs is triangular and resembles in 

 position that of S. plumosa. The first foot has long, pale 

 golden, iridescent bristles, which in the preparation pass for- 

 ward and inward, so that they cross each other toward the 

 tips, which show only a trace of a curve. They and the next 

 two groups are studded with Loxosomce, which extend likewise 

 on the foot at the base and present buds at various stages. 

 In structure the dorsal bristles (PI. XII. a. fig. 3) have narrow 

 segments at the base and for a long distance outward ; then 

 toward the tip the segments increase in length but irregularly, 

 two, three, or four short segments being followed by a 

 longer one, and so on to the delicately tapered tip. In some 

 instances the smaller segments are incomplete, the lines 

 running inward only partially. The ventral of the first set 

 are a little shorter, but show the same structure. The dorsal 

 and ventral bristles of the second and third groups are shorter, 

 and the ventral of the third have increased in strength, 

 forming a stiff fan of rather long bristles which spread up- 

 ward and inward, so that much of the fan is seen from the 

 ventral surface. They taper from base to apex, and the 

 segments increase gradually in length toward the tip, which 

 is generally abraded, apparently from use in the tunnel in 

 the mud. The fourth foot has slender dorsal bristles, and 

 ventrally a row of stiff flattened hooks (PI. XII. a. fig. 4) with 

 closely articulated shafts, and broad flattened tips shaped like 

 a hedge-bill with a well-marked hook. Oblique stria} occur 

 as the transverse lines wane. Besides these is a form 

 simply curved like a tapering spatula and having articula- 

 tions nearly to the tip. The dorsal bristles form somewhat 

 stiff fans directed obliquely forward and upward to the 

 posterior end of the fragment. The ventral hooks, again, 

 remain only for a short distance of the broad knife-shape, 



