Gattij Marine Laloratory, St. Andreics. 101 



Die raediau line anteriorly is tlio flattened conical prow seen 

 ia the form above mentioned, but it has distally the filiform 

 process so characteristic of the species. From the basal 

 process the long and rather narrow glandular keel passes 

 backward almost to the posterior border. Tlic long nuchal 

 organs lie at each side, and they slightly bend outward 

 anteriorly, but do not reach the margin, which has two 

 broad lateral flaps in front of the notches, and a narrower 

 and often more or less erect border between the notches. 

 The fused pro- and peristomial segments have the large 

 aperture of the mouth ventrally, and it is usually marked by 

 a series of radiating furrows, M-hich are somewhat regularly 

 arranged on the prominent postei'ior lip. Anteriorly a 

 ridge runs forward to the notch on each side of the flattened 

 base of the anterior process. In partial protrusion the 

 proboscis forms a button-shaped papillose organ, but in full 

 extrusion a considerable bladdei*-like smooth region with a 

 terminal fissure occurs beyond it. The papillae on the basal 

 region in extrusion arc bluntly conical, large, and prominent, 

 four or five papilke occurring in each row anteriorly, and 

 nine or ten occurring, as i^rwidsson observes, in each row 

 })osteriorly. Reddish mud oozed from the mouth on the 

 slightest pressure. The fine mud swallowed by the annelid 

 contains many organic elements, besides spicules of sponges 

 and minute sand-grains. An occasional larval annelid 

 occurs. 



The body is more or less rounded dorsally, slightly flattened 

 behind the anterior third ventrally, and marked by a median 

 streak, which becomes a ridge posteriorly. A distinct 

 constriction behind the cephalic region, affecting three or 

 four segments, occurs anteriorly. There are nineteen 

 bristled segments, and four without bri-tles posteriorly. 

 Large forms exceed 100 mm. in length, and the walls of the 

 body posteriorly are thinner than in P. pratermissa, so that 

 from flattening the diameter of large examples is 4-5 mm. 

 The anal funnel is comparatively small, has a prominent 

 anal cone with a valve, a long ventral cirrus, and twenty-two 

 to twenty- five (Arwidsson gives twenty-seven) shorter cirri, 

 which vary in length in diflerent specimens. Pigment is 

 usually absent in spirit-specimens, but in one the anterior 

 region is mottled with brownish red. The anterior bristled 

 segments from the first to the anterior part of the eighth 

 are glandular, but the glandular elevations at the row of 

 hooks thereafter are absent. Arwidsson gives in detail the 

 arrangement of the glands in the various parts. The 

 segmental organs occur in bristled segments six to nine. 

 The first, second, and third segments are, as mentionedj 



