112 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 25 



Chaetozone gracilis is most clearly distinguished from other species 

 of the genus in that it nearly lacks notopodial acicular spines, and 

 neuropodial spines are falcate, with the distal tip delicately serrated. 



C. gracilis was first described from abyssal mud off Santa Catalina 

 Island ; it has since been found in slope depths of southern California 

 and western Canada (Berkeley and Berkeley, 1952a, p. 37). 



Genus Tharyx Webster and Benedict, 1887 

 Type T. acutus Webster and Benedict, 1887 



Species of this genus are among those most frequently encountered in 

 southern California in shelf depths. At least 5 species are known to be 

 present, and others may be expected. Their specificity is sometimes 

 obscured because of the lack of strong morphological characters. Im- 

 mature individuals are most difficult to determine specifically. Color 

 markings, sometimes present in adult individuals, are largely lacking 

 from juveniles or specimens preserved in alcohol. The species named 

 herein are briefly diagnosed in the key (see above). 



Tharyx multifilis Moore, 1909 



Tharyx multifilis Moore, 1909a, pp. 267-268, pi. 9, fig. 43. 



Collections. Southern California, from intertidal and shallow depths, 

 in silty and mixed sediments. 



Length is 50 to 60 mm, segments number 200 or more. The body is 

 large and robust ; it tapers posteriorly to a slender pygidium and is not 

 inflated in its last few segments. The prostomium is a short, anteriorly 

 depressed lobe without eyes and with a midventral, longitudinal groove. 

 The buccal region is large, appears inflated, and has only partial fur- 

 rows marking the segmental lines. All segments are short, uniannular, 

 and not unusual. Setae in both notopodia and neuropodia are slender 

 and capillary, with those of the upper branch the longer but otherwise 

 the same as the neuropodial setae. Lateral branchiae are long, filamentous, 

 inserted immediately above the notopodium in all regions of the body 

 except that they seem to be lacking in many of the posterior segments. 



Tharyx multifilis was first described from intertidal regions of south- 

 ern California. It has since been found to attain its greatest abundance in 

 southern California, off the Los Angeles breakwater, in silty sediments. 



