1903.] NATURAL SCIENCES OF PHILADELPHIA. 453 



and 4th parapodia. in which they he just ventrad of the other setse 

 and next to the postsetal lobe. 



Beginning with the 5th parapodium, simple uncini replace the com- 

 pound ones just described, though they are only fully estabhshed sev- 

 eral somites further caudad, and are usually two in number throughout 

 the anterior branchial region, but may be 3, or even 4, toward the 

 posterior end. They are yellow, stout, nearly straight or slightly bent 

 back (this direction being opposite to the compound uncini), sHghtly 

 swollen subterminally, the end bifid with two stout, ventrally 

 directed processes, of which the proximal is the larger; guard ob- 

 liciuely fan-shaped and striated ; stem rather coarsely striated, which 

 is not the case with the compound uncini. 



Slender, pointed setae occur in all of the parapodia except the first, 

 arranged in typical somites in two horizontal rows above and below 

 the uncini. the dorsal one being larger. These are the only seise of 

 sufficient length to reach beyond the postsetal lobe, and anteriorly 

 even these do not. Stems much slenderer than the uncini, only the 

 larger ones exhibiting any color, bent dorsad abruptly but slightly at 

 about the middle of the exposed portion; a reverse but more gentle 

 bend in the opposite direction, bringing the terminal part into a direc- 

 tion parallel to the base, occurs in the setae of the posterior half of the 

 body; flange always on ventral side, widest at angle of seta, disappear- 

 ing terminally, leaving an acute very brittle point; both stem and 

 flange obliquely striated. On the 4th parapodium the flanged setse 

 are smaller and fewer; on the 3d and 2d only the dorsal bundle occurs, 

 reduced on the latter to 2 or 3 very small, acute, scarcely winged, color- 

 less setae. Posteriorly also the winged portion becomes reduced in 

 length. 



The 4th kind of seta is the most numerously represented but the least 

 conspicuous of any; a single one appears in the dorsal bundle of the 

 2d parapodium, but in all succeeding parapodia a close bundle of 

 many occurs between the postsetal process and the dorsal fascicle of 

 flanged setae. They are of very unequal length, the longest being on 

 the posterior side, but none equal ^ the length of the flanged setje. 

 They have slender stems terminated by a delicate funnel-shaped 

 enlargement with a crenulated or toothed margin. 



Sagami Bay, 3,698, 153 fms.; 3,704, 94 fms.; 3,707, 63-75 fms.; 

 Suruga Bay, 3,738, 167 fms., type. 



