284 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 15 



This species was originally described from three specimens in which 

 the transition from thorax to abdomen was at segment 14, 16 and 20 

 respectively; in the present individual the transition is abrupt after seg- 

 ment 23. The branchiae are absent from the thorax and begin on the 

 first abdominal segment. The prostomium is acutely pointed and longer 

 than wide; the peristomium or first segment is a little longer than the 

 prostomium and intermediate in width between the prostomial base and 

 the first setigerous segment. There are no ventral cirri or subpodial 

 lobes. In the thorax the notopodia have a long triangular postsetal lobe 

 and neuropodia are represented only by very low postsetal ridges. Thor- 

 acic neuropodial setae are almost entirely dark brown with smooth 

 brown acicular spines, except for an occasional long, capillary seta in a 

 few of the anteriormost segments, irregularly strewn in the fascicles 

 with the brown spines. The first seven neuropodia have spines in double 

 rows; thereafter the rows are single. The rows are longest in middle 

 thoracic segments and diminish in the last 8 thoracic segments so that 

 only about 4 spines are present in the last two such segments. The pig- 

 ment of the neuropodial spines is most intense in middle thoracic seg- 

 ments and in the lowermost spines ; the uppermost in the series are pale. 



Abdominal notopodia consist of a long, tapering postsetal lobe and a 

 fascicle of long, slender setae accompanied by 3 to 6 furcate setae in 

 which the tines are unequally long. The corresponding neuropodia ter- 

 minate distally in a bulbous lobe as originally shown and have a few 

 long, slender setae and several pale, very slender embedded acicula. 



This individual differs from the original account in that the transi- 

 tion from the thorax to the abdomen is at a later segment ; but since it is 

 variable in the type collection, the difference may not be significant. The 

 proportions of prostomial and peristomial lengths differ but no more 

 than in some other species of the family. 



Distribution. — Scoloplos treadwelli was first described off Puerto 

 Rico in 12-18 fathoms with mud and shale, 161-172 fathoms, sand and 

 mud, and 97-120 fathoms, coral. The greatest extension of its range is 

 the present record which comes from off Acapulco, Pacific side of Mex- 

 ico, in 13 fathoms on a bottom of sand and silt. 



Scoloplos (Leodamas) Kinberg, 1866 

 Type Scoloplos (Leodamas) verax Kinberg, 1866 



Includes Branchethus Chamberlin, 1919. 



The prostomium is acutely pointed and usually prolonged. Ab- 

 dominal neuropodia have acicula which are heavy, single and project 

 from the parapodium. Branchiae are first present from about the fifth or 



