10 Prof. M'lutosli's Notes from the 



hue, and the exposed parts are covered with miuute sand- 

 particles. 



An allied species (AB) occurred under stones between 

 tide-marks both in Guernsey and Herm, with only five pairs 

 of anterior bristles, and shows diiierences from both 

 Potamilla reniformis and P. torelli. The cephalic plate has 

 a narrower collar than in P. reniformis, a feature well 

 marked in the small, pointed, ventral lobes. The edge is 

 smooth at and near the mid-dorsal groove, then at each side 

 is a lateral flap which trends to the lamellae on the ventral 

 surface. These lamellse are smaller than in Sabella pavoninu. 

 Besides the small lamellae which project ventrally, the margin 

 is incurved at the middle line. 



The body is comparatively small, about | of an inch 

 in length, and the number of segments is between sixty and 

 seventy. It is rounded dorsally, with the exception of the 

 region of the dorsal groove anteriorly, slightly flattened 

 ventrally where a median furrow runs from the middle of 

 the sixth scute backward to the tail. The anterior region 

 is composed of live bristled segments and apparently the 

 same number of uncinigerous rows. Posteriorly it tapers to 

 a somewhat pcnnted tail. The branchiae seem to be com- 

 paratively short — like those of Potamilla reniformis, and the 

 pinnse of moderate length or rather short, whilst the terminal 

 filament is long, large, and is often in screw-coils, thus 

 (lifiering essentially from those of P. reniformis, P. torelli, 

 and P. neylecta. Moreover, there are no ocelli on the 

 filaments, and none on the first segment or on the tail. 



The first region of the body has only five pairs of seti- 

 gerous processes. Each bears a tuft of comparatively short 

 bristles, the tips of wliich, unfortunately, had for the most 

 part disappeared — probably from their brittle nature as well 

 well as from rough usage. Those which are perfect have 

 shafts which slightly dilate from the base to rather beyond 

 the middle, then diminish at the neck and swell out at the 

 origin of the wings, tapering thereafter to a somewhat long 

 attenuate extremit3\ At the upper edge of the fascicle are 

 the longer and more slender forms, the shafts of the others 

 being thicker. No trace of spathulate tips is observable. 

 Tlie anterior hooks form a single row, and present a sharp 

 main fang, the rest of the anterior face of the crown above 

 it (about half the extent) being finely serrated in lateral 

 view. As usual in such hooks, when the crown is examined 

 from the front, this region is densely spinous. The posterior 

 outline is more or less straight below the forward bend at 

 the crown, whilst the anterior — also straight immediately 



