Zool.— Vol. I.] JOHNSON— PACIFIC COAST ANNELIDS. 1 77 



also, as that is by far the commonest Fissurellid on that 

 portion of the coast. I have collected a single specimen 

 from the gill-groove of Cryftochiton stelleri, at Bolinas, 

 Marin County, California. This is the only individual I 

 have seen with black pigmentation on the elytra similar to 

 P. pulchra. 



Polynoe pulchra, sp. nov. 

 Plate VII, Figs. 34, 43, 433; Plate VIII, Figs. 50, 50a, 50A. 



Form attenuated posteriorly, like P. Lordi, which this species closely re- 

 sembles. Greatest width in anterior third, thence tapering gradually to slen- 

 der posterior end. 



Prostomium (fig. 34) broader than long, with two peculiar lateral expan- 

 sions adjacent to peristomial somite. Eyes four, placed far back, those of 

 each pair far apart, the anterior pair more distant than the posterior; 

 posterior and anterior pairs of about equal size. The tentacle inserted 

 about half the length of its basal segment into front edge of prostomium; 

 slightly longer than prostomium. Antenna? prolonged from anterior tips of 

 lateral lobes of prostomium, with distinct basal joints, about equal in total 

 length to the tentacle. Palpi thick and fleshy, slightly tapered from base, 

 abruptly at tip, ringed with black near their distal ends. Filamentous tips 

 of all dorsal cirri protrude abruptly from the slightly thickened terminal 

 portion. 



Parapodia (fig. 50) long, dorsal ramus rather slender, enlarged distally, fre- 

 quently achaetous, or bearing a few serrated and notched seta; (fig. 50b). 

 Ventral ramus with a few (6-12) strong, amber-colored, hooked setae (fig. 

 50a), which have a few very minute serrations on the thickened portion near 

 the tip. 



Dorsum usually exposed (but not broadly, as in P. Lordi) between the 

 rows of elytra; transversely marked with brown bands, two to each somite. 

 Elytra (fig. 43) slightly undulate at margin, broadly reniform, adorned with 

 a black or dark brown spot over the elytrophore, and a narrow posterior 

 border of the same color, or else immaculate; very smooth. Epithelial cells 

 small (fig. 43a). Young specimens from Holothuria californica are amber- 

 color, very translucent, and entirely unspotted. Older ones from the same 

 host are suffused with Indian-red, often with a tinge of purple, and have a 

 large central spot of brown on each elytron. 



Number of somites, 48-64; pairs of elytra, 20-33. Elytra are borne on 

 somites 2, 4, 5, 7. ...23, 26, 28, 29, 31. ...51. 



Measurements. — Length, 51 mm.; greatest width, 10 mm. 



This beautiful Polynoid occurs at Pacific Grove as a 

 common messmate (or possibly parasite) of two animals 

 wide apart in the organic scale : Holothuria californica 



