Cfiamberlin — Polychaetes from Monterey Bay. 177 



ARICIIDiE. 

 19. Nainereis nannobranchia Chamberlin. 



One specimen. Previously known from Mendocino. 



20. Nainereis longa Moore. 



Proc. acad. sci. Phil, 1909, p. 264, pi. S, f. 38-42. 

 This is the type locality for this species. 



GLYCERID^ 



21. Glycera robusta Elders. 



Die Borstenwiirmer, 1868, p. 656, pi. 24, f. 31, 32. 

 A rather common species in this region. 



22. Glycera rugosa Johnson. 



Proc. Boston soc. nat, hist., 1901, p. 411, pi. 10, f. 105, 103a. 



23. Glycera nanna Johnson. 



Proc. Boston soc. nat. hist., 1901, p. 411, pi. 10, f. 103, 103a. 



CIRRATULIDiE. 

 24. Audouinia spirobranchus (Moore). 



Cirratulus spirobranchus, Proc. acad. sci. Phil., 1904, p. 492, pi. 38, 

 f. 26 and 27. 



One specimen of this species, like the type, is near 105 mm. in length 

 but is more robust, having a maximum diameter of 7 mm. 



Ambo, gen. nov. 



Characterized in bearing special or dorsal branchiae on a large number 

 of segments beginning with the first setigerous or the one preceding it, 

 with the principal groups on a segment caudad of the first setigerous as 

 in Audouinia. 



Genotype. — A. perbra?ichiata, sp. nov. 



25. Ambo perbranchiata, sp. nov. 



Characterized by the arrangement and large number of the branchiae. 

 The principal groups of these occur on the fifth setigerous segment, where 

 they form a dense multiseriate band continuous across dorsum, no mid- 

 dorsal interval being evident. Special branchia? also occur on about 

 thirty succeeding somites, the two groups, unlike those of the fifth seti- 

 gerous segment, being widely separated by a middorsal naked area. The 

 number of branchial filaments in each group on these segments from four 

 or five down to two. Branchiae of the same group often very different in 

 thickness and length, some, possibly regenerating, being very slender 

 and short. A few special or dorsal branchiae also occur on all the seti- 

 gerous somites in front of the fifth, there being a single special cirrus on 

 each side of the first setigerous segment. In going caudad from the region 

 where only single cirri occur on each side, the cirri come to occur first 



