374 PROCEEDINGS OF THE ACADEMY OF [April, 



series usually of two stouter, deep glistening brown, nearly straight 

 spines (fig. 70). All middle neuropodial setse are quite free from hairs 

 and nearly or quite smooth. Toward the caudal end they become 

 gradually elongated with increasing asperities and finally pale-yellow 

 subcapillary setae roughened with numerous short spines more or less 

 regularly alternating on the two sides (fig. 75). The usual dense 

 fascicle of pinnate setce replaces the ventral neuropodials on II. In 

 this species, so far as can be determined from a single specimen the 

 spiral pennon is less developed than on the other species (fig. 74). 



Notopodial setae consist of stout, fragile spines and flexible fibers. 

 The former (PI. XXXII, fig. 68) are deep lustrous brown and form a 

 conspicuous bristling armature penetrating the felt at the sides and pro- 

 tecting the sides and dorsum of the body for its entire length. They are 

 more or less flattened, slightly curved near the base, then straight, very 

 rigid and tapered to subacute points. The core is striated longitudinally 

 and here and there fractured transversely and the hard outer shell is 

 roughened by numerous small tubercles which increase in size toward 

 the distal end until they are just visible under a magnification of four 

 or five diameters (fig. 67). These spines are arranged in a dorsal and 

 a ventral group on each segment. A'^entral on maddle segments of 

 nine to eleven arranged in a vertical series and rapidly increasing in 

 size from below dorsad, the most dorsal many times larger than the 

 most ventral and more recmnbent on the felt. Posteriorly they 

 become longer and more recumbent and anteriorly shorter and more 

 erect. Dorsal fascicles usually consist of two small oblique rows of 

 five or six but on elytrophorous segments may be limited to a single 

 somewhat longer row. These increase in size postero-caudad, the 

 last of each series being much flattened and very long so that they 

 cross those of the opposite side in an abattis-like arrangement. Ante- 

 riorly they are short, more erect and do not cross. At the extreme 

 caudal end they become quite slender. 



Fibers arise as usual in three tufts, the dorsal felt being formed by 

 the intermediate tufts on all parapodia and by the larger dorsal tufts 

 on elytrophorous segments only. They are exceedingly long and fine 

 with peculiarly hooked tips and interlace to form the even but rather 

 thin layer of felt which in this specimen is free from silt. The ventral 

 or lateral tuft consists of much shorter, coarser, roughened fibers with 

 straight fine points which do not felt but hang in loose fringes behind 

 the parapodia. They correspond to the iridescent fibers of other 

 species but nearly lack this quality and are dull gray and more or less 

 covered with silt. 



