266 THE ANNELIDA POLYCHAETA. 



The prostoniium is wide in proportion to its depth, in anterior view being 

 transversely elliptic in outline. It is comparatively long, being dorsally twice 

 as long as the peristoinium. The surface in general is smooth ; there is a vertical 

 sulcus on the anterior face from between the frontal tentacles ventrad. The 

 palpi are large and conspicuous, thick and subconical, distally rounded. They 

 are contiguous mesally. Each extends outward beyond the side of the pro- 

 stomium. The tentacles are arranged in a transverse ellipse. The frontal 

 tentacles are separated by less than half their proximal diameter; they are sub- 

 cylindric and distally rounded. The dorsal tentacles are each composed of a 

 conspicuous, distinctly annulate and strictly cylindrical ceratophore and a long, 

 smooth style which proximally is as thick as the ceratophore, but gradually 

 tapers distad. The anterior paired tentacles reach to the fifth somite; the 

 ceratophore consists of five very short articles and a distal smooth division 

 clearly more than a third but less than half the total length; the style, stout at 

 base, tapers to a fine point. Each posterior paired tentacle is inserted midway 

 between the corresponding anterior tentacle and the median tentacle, and reaches 

 to somite XVIII or XIX; the ceratophore is a little longer than that of the 

 anterior paired tentacles and consists of six short articles proximally and a 

 smooth distal division less than half of the total length; the style narrows very 

 gradually and uniformly to an acute tip. The ceratophore of the median tenta- 

 cle is shorter than that of the posterior laterals, being nearly equal to that of the 

 anterior laterals; it is composed of five short proximal articles and the usual 

 smooth distal division ; the style is of the same form and nearly of the same length 

 as that of the posterior laterals. (Plate 40, fig. 3). 



The peristomium dorsally is very short, being in the middorsal line not 

 more than half the length of the prostomium or of the length of the second 

 somite. On each side it projects conspicuously forward to embrace the pro- 

 stomium. The lower lip is abruptly elevated above the level of the lateral 

 surface on each side and is sharply limited ; it is broad and but slightly narrower 

 caudad than across the anterior end; the anterior margin is in the form of a 

 very obtuse V with the apex, which is caudad, narrowly truncate and each arm 

 at its extreme outer end curving a little more directly ectad; there is a sub- 

 quadrate area outlined on the middle of the surface by weak furrows. (Plate 

 40, fig. 5). The tentacular cirri are long and slender, each reaching forward 

 beyond the bases of the frontal tentacles. (Plate 40, fig. 3). 



The first few metastomial somites are rather strongly arched dorsally, the 

 arch becoming wider and lower caudad. Ventrally the somites are moderately 



