chamberlin: pacific coast polychaeta. 253 



5. Hesperonoe senilis, sp. nov. 



Plate 1, fig. 1-4. 



Differing decidedly from Antinoe macrolepida Moore, known from the Gulf 

 of Georgia and northward, in having the peaks of the prostomium conspicu- 

 ously large, pointed, and widely separated. Anterior eyes much smaller than 

 in that species, but little exceeding the posterior. Median tentacle slender, 

 tapered, not morq. than twice as long as the prostomium measured to anterior 

 ends of peaks; lateral tentacles very much smaller as usual, but little exceed- 

 the ceratophore of the median tentacle and shorter than the prostomium. 

 Prostomium longer than wide. Palpi very long and evenly tapered, much 

 exceeding the median tentacle. Tentacular cirri similar in form to the palpi 

 but shorter and proximally more slender; the inferior one thicker than the 

 dorsal. Body ventrally widest near somite XII, from where it narrows 

 evenly and moderately caudad, proportionately much wider than in macro- 

 lepida, the ventral width much exceeding the length of parapodia exclusive 

 of cirri and setae. No distinct ventral groove. Nephridial tubercles begin- 

 ing on VII, slender. Elytra overlapping moderately medially and cephalo- 

 caudally. Those of first pair circular, the others elliptical; second, third, 

 and fourth pairs broadly and shallowly incurved on anteroectal side, the first 

 of these the most strongly so. Elytra thin, marginally transparent, elsewhere 

 translucent; surface, excepting a narrower border, covered with low, light 

 colored tubercles, each tubercle bearing a dark spinous point; the tubercles 

 not crowded, becoming much smaller on anteroectal part of scale, the posterior 

 ones commonly more or less laterally compressed; edges smooth excepting 

 on external side where there are fine short cilia. Notocirri much exceeding 

 the setae, slenderly and evenly tapered with no sub terminal enlargement; 

 cirrophore large. Neurocirri attached distad of middle, slenderly subulate, 

 obviously shorter than the shortest setae. Each ramus of parapodium sup- 

 ported by a single, stout, evenly tapering aciculum, the notopodial stouter 

 than the neuropodial. Notopodial setae numerous but fewer than the neuro- 

 podials; the prevalent type shorter but much stouter than the stoutest neuro- 

 podials, a few most dorsal ones very short. In addition in the ventral part 

 of the fascicle a number of very fine but longer capillary setae with widely 

 separated teeth along one edge. The supracicular neuropodials are of the 

 Antinoe type, being slender with exceptionally long and fine smooth tips. Of 

 the much more numerous subacicular setae the majority are coarser than the 

 supraoculars with tips notably shorter, approaching more the Eunoe type. 

 Below these a group of much finer setae with shorter heads set at a greater 

 angle to the shaft. The general color of parapodia and body at present light 

 brown, the body above and below with a paler median longitudinal band; 

 elytra greyish or colorless. Last few segments of body of type missing. 



