Zool.— Vol. I.] JOHNSON— PACIFIC COAST ANNELIDS. I 73 



Cephalic cirri and dorsal cirri smooth, slightly thickened below the apex 

 (the tentacle being the most so), ringed with black at the thickened place. 

 The antenna? are decidedly shorter than the tentacle and peristomial cirri 

 and about equal to the buccal cirri. Dorsal cirri, except the most posterior, 

 of about equal length throughout, scarcely if at all surpassing the ventral 

 setae. Ventral cirri short, fusiform. Palpi very large, white or grayish, grad- 

 ually and uniformly tapered from a thickened region near the base to the 

 fine, filamentous tip. Minutely papillated all over, except at extreme base. 

 Anal cirri extremely short, fusiform. 



Parapodia very stout (fig. 48), much wrinkled near base. Dorsal ramus 

 conical, diminutive, usually achastous, or with one or two minute setae. One 

 or two of the parapodia in posterior part of body usually asymmetrical, hav- 

 ing an elytron on one side and a dorsal cirrus on the other (fig. 49). 



Ventral setae (fig. 48a) very large and stout, toothed near extremity, ser- 

 rated for a short distance below the apex. Uppermost much the thickest, dark 

 amber color (fig. 486). 



Elytra varying from irregularly reniform (fig. 42) anteriorly, to nearly or- 

 bicular along all the middle and posterior portions of the body. Smooth 

 and entirely destitute of papillae or tubercles. Ocellate, and mottled with 

 blotches of iron-gray pigment, which is distributed in the epithelium of both 

 sides of the elytron, as appears very distinctly when the elytron is viewed by 

 transmitted light (fig. 42a). 



Nephridial papilla; about twice as long as thick, enlarged at extremity, 

 ringed with black. They extend from the eighth somite to the pygidial. 



Colors dark-reddish on dorsum, iron-gray on elytra; each elytron with an 

 imperfect ocellate spot; below, unpigmented. A dark spot at base of each 

 dorsal cirrus; dorsal ramus dark. 



A considerable portion of the dorsum is usually exposed in both young 

 and old specimens. 



Measurements. — Length, 165 mm.; width, 12 mm. 



Habitat. — San Pedro, San Diego (Pt. Loma) 1 , commensal 

 with large Ampkttrite. 



This magnificent Polynoid has been found only as 

 a tube-commensal with a large species of Amphitrite, and 

 is southern in its distribution, The dimensions above given 

 are taken from alcoholic specimens which have undergone 

 the usual amount of contraction. A fully extended, living 

 specimen of the largest size would measure not less than 

 23 cm. Thus the present species ranks among the largest 

 of its family and of its class. 



It is worthy of note that the Polynoidag of excessive 



1 We have obtained 110 specimens from San Diego Bay; but recently two were kindly 

 collected for me (together with several other Polycheetes from that region) by my friend 

 Prof. Win. M. Wheeler, at Point Loma, near the entrance to the Bay. 



