1909.] NATURAL SCIENCES OF PHILADELPHIA. 287 



filaments, the ends of which reach in extension scarcely beyond the 

 ends of the collar setae. The palpi, arising immediately beneath the 

 tentacles and above the mouth, are more than twice as long and four 

 or five times as thick as the tentacles, blunt, slightly tapered and finger- 

 like, not at all spatulate or flabelliform, the venter with a deep longi- 

 tudinal groove, the margins of which are merely slightly crenulate 

 and not lobed. Mouth a transverse slit or a more rounded opening 

 with lobed margins normally hidden at the bottom of the collar. 



The collar region, reaching back as far as the first ordinary somite, 

 probably represents the peristomium alone or perhaps both I and II. 

 It consists of a short achaetous posterior ring and a cylindrical or 

 funnelform, thin membranous collar with small dorso-median, ventro- 

 median and lateral incisions in its border, the whole being about as 

 long as the three somites next following. It bears the broad fan- 

 shaped conjoined fascicles of notopodial and neuropodial seta? form- 

 ing a close continuous series, which, like a palisade of stakes, build 

 up the collar to double its own height. When the cephalic appendages 

 are extended they are embraced by the peristomial collar and setae 

 cage and when retracted are concealed within them, the setse of the 

 two sides drawing toward the middle line. The collar, which clearly 

 represents a pair of parapodia, is thickly studded with cutaneous 

 papillae, those at the base of the setae being very numerous, much 

 elongated and slender, with filamentous stalks bearing terminal knobs 

 and often reaching the tips of the setae. 



Succeeding segments are much shorter, their length never exceeding 

 one-third the width, and quite simple, with the intersegmental papillae 

 quite high between the parapodia but elsewhere very slightly developed. 

 Anteriorly for a short distance the body is subterete or subquadrate, 

 but for most of its length, owing to the position of the parapodia, is 

 subtriangular in section, the somewhat truncated apex being ventral, 

 the nearly flat base dorsal and the usually somewhat convex sides 

 lateral. In places where the body is much distended this convexity 

 or bulging may be sufficient to give to it a cross-section approaching 

 the circular. As noted above the body-wall is thin, easily ruptured, 

 and semi-translucent. Most of the surface is smooth and bears few and 

 small papillae, but on the dorsum and about the parapodia they 

 become larger and more numerous, those on and near the notopodia 

 being largest of all and, like the collar papillae, bearing very large 

 terminal knobs, and when extended reaching to the tips of the setae 

 and giving to the notopodia the aspect of erect tufts or tassels. The 

 neuropodial papillae on the other hand are much shorter and, like 

 those scattered over the dorsum, bear small terminal knobs. 



