1914] Treadivell: Poly chaetous Annelids of the Pacific Coast 217 



tufts. Its dorsal surface is also marked with transverse annulations, 

 the posterior border of each slightly overlapping the one behind it 

 so as to resemble clapboards. These annulations are found in suc- 

 ceeding somites, but their overlapping is less marked posteriorly. 



The mouth has prominent anterior and posterior lips. Two 

 grooves, appearing at the base of the prostomium, diverge to pass 

 along the lateral edges of the mouth and, continuing posteriorly, form 

 the lateral edges of the ventral ''sole." Both dorsal and ventral lips 

 are provided with many small scale-like epidermal thickenings ar- 

 ranged in rows resembling the pavement teeth of an elasmobranch. 



The ventral surface of each of the first seven setigerous somites 

 is flat, and divided on either side by a longitudinal furrow. Behind 

 the seventh somite the whole surface of each is much depressed, form- 

 ing, in preserved material, a deep longitudinal groove which extends 

 to the posterior end of the body. All somites are annulated. An- 

 teriorly, each has three annulations, of which the first and third are 

 biannulate on the dorsal surface. The ventral surface retains the 

 triannulate condition throughout the entire body except for the last 

 four or five somites, where it disappears. Dorsally, the surface first 

 becomes quadriannulate, then biannulate, and the annulations finally 

 disappear entirely in the last nine somites. 



The anus is posterior and is surrounded by a ring of about thirty 

 cirri, of which the two ventral ones are much longer than the others. 

 The cirri are thick and almost spherical in form. 



On the ninth and tenth setigerous somites there are numerous 

 small glands, the openings of which extend nearly to the mid-dorsal 

 line. They are especially numerous on the tenth somite, where the 

 skin containing them shows a swollen area. 



The parapodia have two thick presetal lobes throughout the body. 

 The setae of the first setigerous somite are arranged in a dorsal and 

 ventral bundle, each containing about fifteen. Each dorsal seta is 

 long and curves gently to a moderately acute apex. Each has a nar- 

 row wing on its convex surface which does not continue to its apex 

 (pi. 12, fig. 35). The basal portion of each has minute longitudinal 

 striations. Most of the ventral setae were broken, but those which 

 remained were similar in form to the dorsal ones. 



Farther back, the setae become more prominent (pi. 12, fig. 36, 

 a parapodium of the 14th somite). Ventrally there is a tuft of setae 

 essentially like those of the first setigerous somite. At first the dorsal 

 tuft has a few setae like those of the ventral tuft, but, dorsal to these, 



