ONUPHIS CRASSISETOSA. 295 



present on parapodia from the sixth to the fifty third inclusive, a large propor- 

 tion of the somites thus lacking them. Its position with reference to the other 

 Pacific forms having all branchiae simple is shown in the following: 



Key. 



a. Anterior hooded crochets distinctly dentate and usually distinctly compound. 

 b. Anterior crochets tridentate. 

 c. Branchiae beginning on the first parapodia. 



d. Eyes present; inner left plate of maxillae II with five teeth, outer with six. 



e. Right maxilla III with ten teeth; upper tooth of compound crochets short, the median 



tooth extending outward beyond it, the lowermost tooth blunt. .0. elegans (Johnson). 



ee. Right maxilla III with seven teeth; upper tooth or fang of compound crochets very long, 



projecting widely outward beyond the others, the lowermost tooth slender and acute. 



0. holobninchiata Marenzeller. 

 dd. Eyes absent; inner left plate of maxillae II with eight or nine teeth, the outer with seven 

 (upper tooth of compound crochets long, projecting beyond the others). 



O. iridescens Johnson. 

 ce. Branchiae beginning on the third or on more caudal parapodia. 



d. Branchiae beginning on the tliird or foMth parapodia and continuing nearly to end of body; 

 fang of compound crochets short, not rounded, not projecting outward beyond the lower 



ones O. -pallida (Moore). 



dd. Branchiae beginning normally on the fifth parapodia and absent from at least the last 

 forty-four somites; fang of compound crochets much larger and proportionately more 

 slender, distally rounded, projecting beyond the other teeth. .0. geophiliformis (Moore). 

 bb. Anterior crochets bidentate. 



c. Branchiae beginning cephalad of the tenth parapodia; first parapodia not extending far for- 

 ward, not or scarcely surpassing the peristomium. 

 d. Branchiae beginning on the sixth parapodia, and ceasing at or near the fifty third pair; 



median tentacle shorter than the posterior paired ones O. lepta, sp. nov. 



dd. Branchiae beginning on the eighth parapodia and continuing nearly to the caudal end of 



the body; median tentacle longer than the paired ones. . . .0. macrobranchiata (Mcintosh). 



cc. Branchiae beginning caudad of the tenth parapodia; first parapodia curved strongly forward, 



equalling or surpassing the prostomium. 



d. Branchiae beginning on the seventeenth parapodia. .. .0. pycnohranckiata (Mcintosh). 



dd. Branchiae beginning on the twelfth to fourteenth parapodia. 



e. Branchiae beginning on the twelfth or thirteenth parapodia; somite II between two and 

 three times as long as I; crochets of anterior parapodia simple; diameter near 4.8 mm. 



0. hiatidenlaia Moore. 

 ee. Branchiae beginning on the fourteenth parapodia; somite II five times as long as I; 

 crochets of anterior parapodia distinctly composite; diameter 2 mm. 



O. crassiselosa, sp. nov. 

 aa. Anterior ventral setae or hooded crochets not dentate, or but vaguely so; simple. 



Branchiae beginning on thirteenth parapodia O. conchylega Sars. 



OnUPHIS CRASSISETOSA, sp. nov.^ 



Plate 42, fig. 1-6; Plate 43, fig. 1-87. 



The general color is dark yellow. On the ventral surface over the caudal 

 half of each specimen is a median longitudinal series of paler, whitish spots. 



1 crassus, coarse, and setosa, with bristles. 



