1910.] NATURAL SCIENCES OF PHILADELPHIA. 499" 



saucer-shaped plates conspicuously serrate on edge and about equal in 

 size, the lowest closely affixed to the end of the operculum. From 

 this, a little to one side of center, a large rounded hollow column arises, 

 made up of four parts or sections successively decreasing slightly in 

 size, with concave sides and flaring top and bottom, each of which is 

 encircled by a series of elongated spines, longest above; at the base 

 of the lowest one no spines are developed. At the joining of the sec- 

 tions there are therefore two series of spines between which a large 

 saucer-shape plate rests; in this specimen, the third joint is destitute 

 of a plate and some of the spines at the apex have been torn away. 

 Branchial lobes elongated, free, slightly spiral, plume-like, the slender 

 tapered rachis, with a thick, broad or deep, striated, web-like membrane 

 on each side, is strongly curved at the end causing the sides to be 

 unequal. The moderately long, much curled, stout branchiae (about 

 50) arise on the outer side only. Collar conspicuous, entire, varying 

 in depth, a broad, shallow emargination on each side forming a com- 

 paratively narrow, deep, angular median marginal lobe having a 

 noticeable seam-like median depression; the large lateral flaps end 

 on a line with the first torus without forming any lateral nor posterior 

 free border. The thorax, however, conspicuously defined, the seven 

 fascicles of setse in very oblique series; the toii reaching across body 

 nearly in contact along the median line; each is situated in the pos- 

 terior edge of a separate overlapping membrane which forms a free, 

 broadly rounded, outer end with pointed fluke-like side lobes; only 

 on the first do both of them show, and on the sixth or last the posterior 

 one is elongated, extending across the body to the opposite side in a 

 scarcely discernible free border. Collar fascicle small, the superior 

 setse very slender, geniculate and roughened by minute hair-like 

 spines at base of narrow regularly tapered blade approaching the form 

 characteristic of the genus Spirobranchus; inferior setse capillary. 

 Other thoracic fascicles large with numerous rather stiff seta 3 ; the 

 shortest, capillary; median with darker rounded elongated blades 

 and short tips; the longest with short tapered ends. Uncini like 

 Spirobranchus with curved pointed teeth (8 in largest abdominal one) 

 above a more prominent truncated terminal tooth (not twisted). 

 Abdominal seta? comparatively small, slender, tapered, often scarcely- 

 discernible, just pricking through the integument. 



Pomatosteyus stellata (Abildgaard, 1789) was carefully described 

 by Ehlers, 1887. from a specimen from off Florida in 13 fathoms. It 

 has a similar one-lobed collar but smaller operculum and a more elon- 

 gated body of 140 segments. Benedict , 1886, also described and figured 



