176 Prof. M'Intosh's Notes from the 



means for passing the faecal matter out of the aperture of the 

 tube without necessitating the turning of the annelid. At 

 its tip is the vent with a more or less distinct rim which in 

 some is oblique. It is noteworthy that in the preparations 

 this tube is generally dorsal, whereas that of S. alveolata is 

 doubled forward in the ventral groove. 



The next species, iSabellaria alveolata, L., has a cephalic 

 region which differs from that of S. spinulosa in the more 

 beautifully regular arrangement of the paleae of the crown, 

 and in the greater development of the filiform papillae which 

 form a graceful margin to it, and are even seen through its 

 translucent marginal paleae. Moreover, the shortness of the 

 firm buccal region posteriorly distinguishes it from S, spinu- 

 losa. The sloping inner row of paleae guard an elliptical 

 central space, at the anterior end of which are the frilled dorsal 

 margins of the mouth. The crown is supported on two 

 short and massive pillars, but they are connate at the dorsal 

 margin, the only differentiation being a gap in the circle of 

 papilla? and the central line separating the posterior paleae. 

 Looked at from the face, however, a slight incurvation of the 

 margin is observed dorsally and a more distinct one ventralty, 

 where the split between the pillars supporting the crown is 

 very distinct. In this species the marginal papillae sur- 

 rounding the crown. are larger, longer, and more numerous 

 than in S. spinulosa, and are very conspicuous whether 

 viewed from front or rear. 



The outer paleae form a pale golden, translucent, and regular 

 margin to the crown, lying almost horizontally, or with a slight 

 slope upward, and presenting a finely notched continuous 

 edge under a lens. Each palea is shaped somewhat like a 

 cricket-bat with a long tapering handle and unequal 

 shoulders, the translucent and flattened blade being slightly 

 bent at the tip and generally split into five or six strong 

 curved teeth directed to the front, or that side of the blade 

 with the higher shoulder and slight concavity in outline. 

 The second tooth, which occupies nearly the middle of the 

 blade, is longest, and is followed by three or four smaller. 

 The blade is marked by transverse striae, which are finest on 

 the translucent tip, and a kind of keel occurs near the 

 higher shoulder, for the shaft is more or less rounded or 

 angular, whilst the blade is flattened. The blades at the 

 dorsal edge are a little longer, and their tips show less 

 friction. The middle palea? have slightly shorter blades, the 

 tips of which are sometimes frayed, and the curve in front 

 differs, in so far as a tendency to slope backward distally 

 is noticeable. Those at the ventral edge show the latter 



