136 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 22 



Family CAPITELLIDAE 



At least seven species in five genera are represented. They may be 

 identified by the following key. 



Key to species 

 1. Thorax consisting of 8 setigerous segments 



capitellid, unknown sp. 



1. Thorax consisting of 10 setigerous segments .... 



Mediomastus glabrus 



1. Thorax consisting of 11 setigerous segments ... 2 



1. Thorax consisting of 12 setigerous segments .... 

 Leiochrides hemipodus 



2. All thoracic setigerous segments provided only with pointed 

 setae 3 



2. Thoracic parapodia provided with pointed setae and hooks 

 Neoheteromastus linens 



3. Last 3 thoracic neuropodia with long handled hooks 

 Notomastus precocis 



3. Last 3 thoracic neuropodia with setae 4 



4. Thoracic segments areolated . . Notomastus magnus 

 4. Thoracic segments smooth .... Notomastus spp. 



Genus LEIOCHRIDES Augener, 1914 



Leiochrides hemipodus, new species 

 ? Leiochrides sp. Hartman and Barnard, this volume, pp. 31, 44. 



The type is selected from San Pedro Basin (Sta. 2798) ; many others 

 are from San Pedro, Santa Catalina, San Nicolas, West Cortes, San 

 Clemente, East Cortes, Long and Velero Basins and from Patton escarp- 

 ment. The body is slender, cylindrical and moderately small. Total length 

 may not exceed 30 mm, of which the thorax is 5.3 mm, and 28 abdominal 

 segments measure 19 mm. None of the specimens is complete but the 

 total number of segments may be about 50. Separation between thorax 

 and abdomen is not marked except for a change in parapodia, where 

 setae are abruptly replaced by uncini. The prostomium is a short, bluntly 

 rounded lobe without eyes. The thoracic epithelium, like that of the 

 abdomen, is smooth and glistening. The peristomium or first visible seg- 

 ment lacks parapodia and is somewhat longer than the next or first 

 setigerous segment. This has notopodia, but lacks neuropodia. The next 



