66 THE ANNELIDA POLYCHAETA. 



twenty ninth, thirty second, thirty fifth, thirty eighth, forty first, forty fourth, 

 forty seventh, fiftieth, fifty third, fifty fifth, fifty seventh, sixtieth, and possibly 

 on one or two others, the condition of the caudal end making it difficult to be 

 certain; the total number is thus a little above twenty-five pairs. 



The parapodia are conspicuously elongate as in the inunediately related 

 forms, each, exclusive of its acicular process, being about as long as its somite 

 and, inclusive of this, much longer. Each is, at its broad base, strongly com- ' 

 pressed in an anterocaudal direction; in view from cephalic or caudal side, it is 

 seen to narrow strongly to near the middle of its length, from where the neuro- 

 podial branch continues of nearly uniform width to the distal end which is obhque, 

 its anterodorsal end elevated, and the aciculum passing through it. The noto- 

 podium is a small but clearly separated lobe arising on the dorsal surface near 

 the base of the neuropodium; the ventral edge of its distal end is prolonged 

 into a slender acicular process similar to that of the neuropodium ; the aciculum 

 shorter and more slender than that of the nem-opodium. 



The parapodial cirri are all lost and nothing definite concerning them can 

 be affirmed from examination of the type. 



There is a single aciculum in each branch of the parapodium. The noto- 

 podial aciculum is yellowish, the coarser and longer neuropodial dark brown. 

 Both acicula project widely beyond the tips of the acicular processes. No 

 notopodial setae are detected in the type. On the distal end of the neuropodium 

 is a group of fine, delicate, and transparent setae which are very much shorter 

 than the projecting ends of the acicuh. These setae are flattened structures of 

 vitreous appearance; viewed from broad surface each is seen to be parallel- 

 sided from the base to a triangular tip of which one side is nearly straight, the 

 other oblique; the tip is entire, not at all incised or bifid, though it is weakly 

 indented or notched at the base on its more oblique side and less so on the 

 opposite one; serrations occur along both borders, and along the ridge the 

 arrangement and development of these is very regular, the serrations not devel- 

 oped on the acuminate terminal division or these vaguely developed on the more 

 obhque side alone; the thickened serrate edges seem to be bent up as far as the 

 tip so that the seta appears concave; in side view the seta is narrow, the tip, 

 over which the serrate thickened borders do not extend, appearing abruptly 

 much thinner and very acute. (Plate 9, fig. 7, 8). 



Locality. Off Panama: Sta. 4,621 (lat. 6° 36' N., long. 81° 45' W.). 

 Depth, 581 fms. Bottom of green sand. Bottom temperature, 40.5° F. 21 

 October, 1904. One specimen. 



