492 THE ANNELIDA POLYC'HAETA. 



elongate, notopodial ridge which bears a series of long, stout, paddle-shaped 

 paleae. On each somite above this there is a well-developed dorsal cirrus or 

 branchia. 



The abdominal somites as usual are not clearly separated. They decrease 

 in width caudad, at first gradually, and then, at the caudal end, very abruptly 

 to the width of the fecal tube. Dorsally the abdomen is strongly convex, with 

 a thin, semitransparent wall through which the viscera are visible. The ventral 

 surface is flat, and mesally longitudinally grooved, with the walls thicker. 

 The notopodial or uncinigerous ridges, or tori, on the anterior somites extend 

 from the gills to the edge of the flat ventral surface, where each ends in a free 

 lobe projecting over the plate-like neuropodial process bearing the ordinary 

 setae. The upper end also projects freely. Caudad the tori become much 

 shorter but remain of the same height, so that the free ends come to project 

 over a constricted base and give each torus the form of a battle-axe. The 

 branchiae, like those of the thoracic region, are well developed on the first seven- 

 teen to nineteen somites, thereafter disappearing abruptly. Each is marked with 

 a longitudinal dark stripe. 



The faecal tube is not complete in any of the type-specimens. Its proximal 

 portion is bent forward and lies in the ventral abdominal groove, as usual. Its 

 walls are thin. There are no indications of parapodia. 



The inner opercular paleae number from twelve to sixteen on each side. 

 They are dark-colored, stout and straight, narrowing distad to the narrowly, 

 acutely rounded tip. Each shows a homogeneous cortex and a densely fibrillar 

 medulla and also shows some cross-striations, which are often vague. (Plate 

 75, fig. 3). The outer opercular paleae on each side number from twenty-five 

 to thirty-two. They extend obliquely forward. Each is pale and subtrans- 

 parent, slender, widest at base, gradually narrowing at base and then of nearly 

 uniform width to the abruptly acutely pointed apex, which is curved mesad. 

 The extreme tip of this apical part is normally fine and acute and bent a little 

 upward; it is easily lost. The medulla is fibrillar and strongly cross-striate at 

 the distal end, or over most of the length, the striae becoming more vague 

 proximad. (Plate 75, fig. 4). 



The neuropodial setae of the four parathoracic somites are on each arranged 

 in a single longitudinal series and project ectoventrad. In the type there are 

 from five to seven in each series. They are coarse and paddle-shaped with the 

 blade somewhat curved and its apex pointed. Longitudinally fibrillar, with 

 the end often frayed through ruljbing. At their bases are the usual shorter. 



