SABELLIDES AND SERPULIDES 239 



SPIRORBIS EXIMIUS sp. nov. 

 pi. xxxix, fig. 9 ; pi. XLI, figs. 7, 18, 20; pi. XLIII, figs. 6, u, 17. 



Type locality. Pacific Grove, California. 



Although but a single specimen, which was destroyed in getting at 

 the animal, was found attached to a Serpula tube, it is noted on ac- 

 count of its very distinctive operculum plate. 



Tube tapered, with a conspicuously corrugated surface, forming a 

 small coil, whether dextral or sinistral was not ascertained. 



Animal with 3 thoracic and about 18 posterior segments; eggs 

 showing a distinct nucleus were in the posterior part of the body- 

 cavity. Collar membrane very conspicuous ; number of branchiae not 

 accurately determined. 



Calcareous plate on the operculum unusually large, elongated, with 

 large basal lobe having a distinct hook-like projection on one side, sim- 

 ilar to that found on the operculum plate of S. cornuarietis, as figured 

 by Marion and Bobretzky in 1875 (pi. 12, f. 27, Z?). 



Superior setae of the first fascicle with conspicuously serrate edge 

 and spiny posterior fin-like expansion ; those of the other fascicles nar- 

 row smooth-edged blades, three odd ones with comb-like ends in the 

 third fascicle. Posterior brush-like setae very small. 



SPIRORBIS MARIONI Caullery and Mesnil 1897. 

 pi. xxxix, figs. 26, 27 ; pi. XL, fig. 16. 



Type locality. Panama. 



Small, opaque, more or less regularly coiled, dextral tubes attached 

 to specimens of Callopoma from La Paz, Lower California, and 

 Panama, also to valves of Barbatia from Acajutla and Libertad, Cen- 

 tral America, and to a conglomerate mass of worm tubes, coral, bryo- 

 zoa, etc., from Guaymas, Mexico, resemble the larger sinistral S. 

 quadrangularis Stimpson, in being four-sided. The upper surface 

 has a deep median groove and two conspicuous ridges or carinae, one 

 defining an inner shoulder around the small, deep, central cavity, and 

 the other an outer shoulder, the entire surface often roughened by 

 growth lines. 



The calcareous plate on the operculum differs from fig. 6 given by 

 Caullery and Mesnil, only in the smaller central protuberance, a feature 

 which is undoubtedly variable. 



The collar seta? have coarsely crenulate blades and fin-like bases ; 

 the other setae are long, regularly tapered blades, with a few odd- 

 ended ones in the third fascicle. 



