10 Prof M'lntosli's Notes from the 



several narrow rings dorsally — giving a finely ribbed aspect 

 to the surface, — the narrow posterior region has only the 

 scgmcnt-jnnction separating each smooth segment. 



Behind the lower lip is ai)])a]'ently a segment with a 

 narrow ventral shiekl. The next bears the first and larger 

 pair of branchiae, each s))ringing from a short stalk which 

 rapidly gives oft" four main divisions; these split up after a 

 brief course into a snb-dichotoraously divided tuft with 

 comparatively short terminal brandies — the whole forming 

 adense arbuscle. The second and smaller pair is on the 

 next segment and has a similar structure. Occasionally a 

 specimen has three branchiae on one side and two on the 

 other, the third being a small independent stem behind the 

 second. 



Ventralward of the second branchial stalk is a small 

 conical papilla which represents the first setigerous process, 

 though it has no bristles. The next setigerous process has 

 a well-developed tuft of bristles, which are pale, translucent, 

 rather brittle, and in two groups; the longer forms have 

 long, straight, deeply inserted shafts, which are nearly 

 cylindrical to the commencement of the wings, from which 

 they taper to a delicate point. The wings have a charac- 

 teristic expansion at the base, and are narrow distaliy and 

 show no serrations. The shorter bristles have peculiarly 

 curved, tapering, serrated tips without distinct rings. 

 Whilst the two setigerous processes behind the branchiae 

 remain isolated and simple, the third presents two processes, 

 viz. tlie setigerous and an antero- ventral papilla, and this 

 continues in the six subsequent feet. The following (from 

 the tenth) setigerous processes, which are somewhat conical, 

 though antero-posteriorly flattened, remain simple, and the 

 first (tenth) of tliis (posterior) series has a small papilla 

 below it at the end of the hook-row. There are twenty 

 pairs of bristle-tufts. 



The first hooks occur opposite the third setigerous 

 process, that is, the second behind the branchiiv, and they 

 occupy the summit of the elevated ridge which extends from 

 the bristle-tuft downward to the ventral groove, and cover 

 in short the external aspect of the ventral longitudinal 

 muscles. They are in a single row in the first six segments, 

 but the rest are in a double row% and this continues to the 

 commencement of the last thirty. After the cessation of 

 the bristles the uncinigerous processes form transverse 

 crescents in each segment, gradually, however, becoming 

 smaller until on the slender terminal region in front of the 

 tail they form a series of papillae, so that the ventral ridge 



