SABELLIDES AND SERPULIDES 243 



Vitreous, strongly grooved and carinated, regularly coiled, dextral 

 tubes agree with eastern specimens from Greenland and the Grand 

 Banks and also with Levinsen's figure. 



The plate on the operculum is similar to that figured by Caullery 

 and Mesnil (1897). 



The collar setae are like one form figured by them, but none appears 

 to have any indication of the notch-like irregularity in the edge shown 

 in the other form ; the serrations are much coarser than in the figure 

 given by Levinsen. 



Sitka, on shells ; Prince William Sound, at Orca, on Cruclgera 

 tubes ; also Queen Charlotte Island, British Columbia, on a specimen 

 of Pachypoma collected by the Geological Survey of Canada. 



SPIRORBIS SPIRILLUM Linne 1760. 



pi. xxvn, fig. 8; pi. xxxin, fig. 15 ; pi. xxxix, figs. 21, 22, 23, 28; pi. XL, 

 fig. 7 ; pi. XLII, figs. 1-5 ; pi. XLIII, figs. 9, 10. 



Type locality. ? Ocean, on Sertularia and other zoophytes. 



The dextral discoid form at the present time considered to be the 

 true S. spirillum of Linne 1 is very common on algae from Cape Fox, 

 Alaska, south to Santa Barbara, California. On the eastern coast it is 

 very common on kelp {Laminaria) and on the interior of the aper- 

 ture of univalves (Buccinum, Sipho, etc.) along the New England 

 coast from Cape Cod to Greenland. The slender ascending form, the 

 true S. lucidus of Montagu, also occurs on bryozoans {Bugula mur- 

 rayana and other branching forms) from St. Paul Island, Bering Sea, 

 along the coast of Alaska, south to Pacific Grove, California, where 

 it is also attached to small univalves. On the eastern coast it occurs 

 on bryozoans, hydroids, annelid tubes, and algae ; often attaining a 

 large size, the var . greenlandicus of Morch (5 1 . porrecta of Fabricius). 



The animals examined from all localities agree in having on the 

 operculum a similar thin, shallow, calcareous plate, with slight inner or 

 basal projection and similarly formed setae ; those of the collar genicu- 

 late abruptly tapered serrate blades, broad and angular at base. 

 There is considerable variation in their length and in the size of the 

 serrations, the latter sometimes being scarcely visible, especially on 

 those of the discoid form from Alaska. 



SPIRORBIS RUGATUS sp. nov. 

 pi. xxix, fig. 3, b ; pi. xxxv, fig. 14; pi. XLIV, figs. 18, 19. 

 Type locality. Sitka. 



On the same fragments of rock with S. variabilis were a few speci- 

 mens, attached singly and in a small colony, of a small dextral species 



