Zool.— Vol. I.] JOHNSON— PACIFIC COAST ANNELIDS. 167 



Polynoe brevisetosa (Kinberg). 

 Plate VI, Fig. 24; Plate VII, Figs. 31, 40, 40a; Plate VIII, Figs. 46, 46a. 



Halosydna brevisetosa Kinberg. Ofversigt K. Vetenskaps Akad. 



Forh., Bd. XII, 1855, p. 385- 

 Ibid, Fregatten Eugenies Resa, Zoologi, 1858, p. 18, Taf. V, figs. 



25 a-h. 

 Lepidonotus insignis Baird. Proc. Zool. Soc. (London), Apr., 1863, 



p. 106. 

 Lepidonotus grubei. Ibid, p. 107. 

 Halosydna insignis Baird. Journ. Linn. Soc. (London), Zool., Vol. 



VIII, 1S65, p. 188. 

 Halosydna grubei. Ibid. p. 189. 



Form variable, from short and robust to rather long and slender (the latter 

 always commensal in tubes of Annelids), about equally rounded at both ends. 

 Somites 37; elytra, 18 pairs, borne on somites 2, 4, 5, 7 . . . .27, 28, 30, 31, 33. 

 Elytra seldom covering the entire dorsum, frequently many of them not in 

 contact with one another. Anus exposed, dorsal, in somite 35, or between 

 35 and 36. 



Prostomium (fig. 31) as broad as long, slightly constricted at base, broadest 

 a little back of anterior pair of eyes, slightly fissured longitudinually at inser- 

 tion of basal joint of tentacle. Eyes four, far back, and distant transversely, 

 anterior pair slightly farther apart than the posterior. 



Antennae, tentacle, peristomial, dorsal, and anal cirri all of moderate length, 

 smooth, cylindrical, slightly bulbous near tip, abruptly tapered to a filamen- 

 tous point. All these cirri characterised by a dark subterminal band, just be- 

 low bulbous enlargement, strongly contrasting with the white apex; and a 

 dusky area, above the joint. (This coloration of the cirri holds for all color- 

 varieties of the species, except in case of the antennae and tentacle, which 

 are frequently dusky for their entire length as far as the subterminal band.) 



Palpi whitish, unpigmented, except in very dark specimens, thickest near 

 base, very gradually tapering to a fine point, beset with minute papilla;, ex- 

 tremely contractile, being about thrice the length of the tentacle when fully 

 extended, but contracting to about one and a half times its length. 



Parapodia (fig. 46) stout, short, scarcely biramous; dorsal ramus very small, 

 provided with short, minute, serrated setae, not reaching beyond tip of 

 ventral ramus. Ventral ramus obliquely truncated, robust, armed with about 

 sixteen seta; in two groups, six above the acicula, ten below. Setae rather 

 short and stout, slightly hooked at tip, which is blunt, with about ten " frills" 

 on their posterior aspect, largest distally (figs. 46, 46a). Ventral cirri on all 

 the parapodia subulate, pointed, of same color as general ventral surface. 

 Anal cirri not longer than average dorsal cirri. 



Nephridial papillae cylindrical, slightly fluted, begin at eighth somite, cease 

 at thirty-fifth or thirty-sixth — 28-29 pairs. 



Elytra extremely varied, broadly reniform to elliptical, first pair nearly 



orbicular, with a few small, short "cilia" on external border (fig. 40); the first 



three or four pairs with large, rounded chitinous tubercles, the remainder 



with minute ones (figs. 40, 40a). Each elytron with an ocella consisting of a 



( 2 ) December 8, 1897. 



