354 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 10 



men killed in tube). The thorax consists of 2 anterior segments, in which 

 the first seems to lack setae; the second is provided with capillary setae, 

 as typical of the genus. The 3 parathoracic segments have paleae in 

 notopodia and slender, though similar, setae in neuropodia. The abdomen 

 consists of about 26 setigers. Uncinigerous tori of the first 10 pairs are 

 broader than long ; after that they are increasingly longer and narrower. 



The opercular crown is conical, asymmetrical, but less so than in P. 

 attenuata (above). The outer row of paleae number about 25 on a side; 

 the middle row consists of about 9 pairs, slightly transversely striated on 

 the external surface; the inner, concealed paleae, numbering about the 

 same as those of the middle row, are pale, inconspicuous. Outer paleae are 

 unique in that the shaft is provided with terminal membrane that is 

 long, spatulate, distally rounded (pi. 37, fig. 84), thin and smooth in 

 texture; normally this appendage is curved inward so that it is directed 

 toward the center of the cone on the exposed surface; in the figure it has 

 been straightened out. The shaft itself terminates in a hard, strong tooth 

 on one side (toward its ventral end) and a similar, though softer, tooth 

 on the opposite side (pi. 37, fig. 84) ; the shaft is weakly striated and 

 delicately toothed on one edge. Paleae of the middle series, forming the 

 outer surface of the cone, are characteristic for having a long shoulder 

 (pi. 37, fig. 85) making up the outer rim of the crown; the exposed 

 surface is weakly striated. Inner paleae are similar to the outer ones, but 

 are much weaker and smaller and are more or less frayed out at their 

 distal end. 



The outer base of the opercular crown is surrounded by about 42 low 

 papillae, forming a low fold that is more or less excavate in the middorsal 

 line but continuous all around. Oral tentacles are present, arranged in 6 

 to 8 crowded rows on a side. Palpi are slender, inconspicuous, to be seen 

 only by laying the oral tentacles to one side; they resemble the oral ten- 

 tacles but are only about two thirds as long. Abdominal uncini, in lateral 

 view, have 5 teeth, but in frontal view they are seen to occur in double 

 rows, as typical of the genus. 



The tubes are constructed of fine, black sand, closely cemented 

 together, the outlines of individuals not discernible. 



P. peruensis differs from other species of the genus in its extreme small 

 size, adult individuals measuring less than 10 mm long; outer opercular 

 paleae have an attached membrane that is broadly rounded, entire, and 

 the middle paleae have a conspicuous shoulder at their external edge. 



Holotype. — U.S. Nat. Mus., no. 20561 ; paratype in AHF. 



Type locality. — Salaverry, Peru. 



Distribution. — Peru. Intertidal. 



