118 THE ANNELIDA POLYCHAETA. 



with its ventral continuation is really the homologue of the ventral cirri of the 

 more caudal parapodia, this view being strengthened by the presence of a swelling 

 at the proximal end of the ventral extension suggesting a cirrophore. The 

 position of the cirrus on the fourth neuropodia indicates a transition, that cirrus 

 being still far distad and on the caudal side; it is thin and distally pointed. 

 The ventral cirrus on the fifth neuropodium is still caudal in position; it is 

 larger than that of the fourth and its free tip is longer, as is also its cirrophore; 

 it is stUl, like that of the fourth, somewhat flattened. The neurocirrus of the 

 sixth neuropodium has assumed a nearly strictly ventral position, the setae 

 beginning distad of it instead of opposite it on the cephalic side; it is more 

 strictly conical, and has the form and proportions prevaihng in the succeeding 

 parapodia. Notocu-ri are present on all parapodia, being attached on the dorsal 

 side and closer to the base than the corresponding neurocirri. They all have 

 thick, conical styles arising from large cirrophores and do not vary much in 

 length, excepting a reduction in size in the slender posterior region of the body. 

 (Plate 17, fig. 1). 



On the first three neuropodia only simple setae are present, these being 

 transparent, stout, distally acute, and strongly ciu-ved, and seven or eight in 

 niunber. They project freely a considerable distance and diverge widely. 

 Apparently but a single seta in each of these neuropodia may occur above the 

 middle, the series being thus practically confined to the ventral half. On the 

 fourth neuropodium, in addition to a series of six stout simple setae, one of which 

 is on the dorsal side, there is on the dorsal side a series of much finer compound 

 setae. (Plate 17, fig. 2-5). In succeeding parapodia the number of simple setae 

 is two, one submedian and one ventral in position, while the number of com- 

 pound setae is much increased, the series extending on the ventral as well as on 

 the dorsal side. The aciculum is single in each neuropodium. It is colorless 

 and tapered from base to an acute tip as usual. The compound setae are also 

 colorless. In them the shaft is straight and is very evenly clavately enlarged 

 distad, the socket not being abruptly wider. The socket is asynmietrical, one 

 side rising liigher than the other in an acutely pointed process which is more 

 or less ciu-ved. The distal piece is relatively long, usually about equalhng in 

 length the free portion of the shaft; it is in outhne somewhat elhpto-fusiform, 

 its greatest width much exceeding that of the shaft; the serrations along one 

 edge are exceedingly fine. 



Locality. Between Peru and Easter Island: Sta. 4680 (lat. 17° 55' S., 

 long. 87° 42' W.). Surface. Surface temp. 68° F. 7 December, 1904. One 

 specimen. 



