SABELLIDES AND SERPULIDES 251 



transverse lines. Calcareous plate on the operculum thin, disk-like, 

 slightly thickened in the center. Setae with simple tapered blades. 



Spirorbis tubaeformis sp. nov. pi. xxxix, figs. 30, 32 ; pi. XLII, figs. 



Small, opaque, white sinistral tubes common on Irish moss ( Chon- 

 drus) from Long Island Sound, southern New England, at New 

 Haven, Connecticut, closely resemble the dextral S. sinistrorsus com- 

 mon on lobsters from Cornwall, England, in the Yale University 

 Museum. The central cavity is smaller than in S. spirorbis Linn6, 

 not showing so much of the earlier whorls, the last whorl being more 

 spreading or trumpet -shaped. In the adult form, which is rarely 

 found, the surface sometimes becomes roughened by irregular growth 

 lines, and the whorls appear rounder and turn upward after the manner 

 of S. lucidus, but in the opposite direction. Collar setae with fine 

 serrate blades and coarser fin-like bases similar to those of S. 

 spirorbis. 



Spirorbis evolutus sp. nov. pi. XLII, figs. 20, 21, 22. 



Smooth, opaque, rather fragile sinistral tubes are attached to the 

 inside of the aperture of a shell {Sipho) from the Grand Banks of 

 Newfoundland. The early whorls are coiled in a regular discoid 

 form, from which the tube stretches out and becomes evolute, more or 

 less irregularly curved, sometimes twisted, increasing abruptly in size 

 and forming a long, somewhat trumpet -shaped portion. They are 

 usually separated, but sometimes spread over one another. In the five 

 specimens stained and mounted in glycerine, the number of branchiae 

 is apparently 9, but this is impossible to determine with accuracy, as 

 they have become much matted in preservation. The operculum is of 

 the ordinary form, with the thin calcareous terminal plate having an 

 unusually long, somewhat spreading basal portion. Body-cavity dis- 

 tended with well-developed eggs. Posterior portion very short, num- 

 ber of segments indeterminable ; only a few setae and scarcely discern- 

 ible uncini were visible. Setae of the collar fascicle slender, long, 

 rounded at base, with faintly serrate edges, one or two with a slight 

 posterior notch. 



Spirorbis formosus sp. nov. pi. xxxix, figs. 18, 19 ; pi. XLI, fig. 22 ; 

 pi. XLIII, figs. 18, 23, 25, 30. 



Small, regularly coiled, dextral, yellowish tubes, very common on 

 gulf-weed (Sargassum} from the Gulf Stream and Bermuda, where 

 they are also found on shells, are ornamented on top with two or three, 



