EXDEMISM IX THE NORTH PACIFIC 49 



ends. The prostomium is an inconspicuous lobe. The ventral part of the 

 peristomium, or lower lip, is modified to form a conspicuous proboscis 

 that projects forward ; it is rugose on both upper and lower surfaces. The 

 upper part of the peristomium is a broad, vaguely three-lobed membrane, 

 accompanied by a pair of large, lateral lobes. The many slender tentacles 

 inserted on its dorsal side are of two kinds. A few anteriormost are larger, 

 broader, longitudinally grooved in their subdistal part and taper distally. 

 Most of the tentacles are slenderer, cylindrical or seemingly annular. 

 Thoracic uncini are long handled ; abdominal hooks are avicular in shape. 

 Artacamella differs from Artacama Malmgren in having 15, instead 

 of 17, thoracic setigerous segments. The proboscis-like organ is rugose 

 instead of papillated. Thoracic uncini have a long handle and are not 

 avicular. The first setigerous is the first uncinigerous segment. Peristomial 

 eyes are present in Artacamella, not absent as in Artacama. 



Artacamella hancocki, new species 

 Plate 3, figs. 1-6 



Collections: Off Los Angeles light, California, in 11 fms. (no. 46b*) 

 (1) ; off Point Fermin light, in 23 fms (no. 80b) (6) ; off Point Fermin 

 light, in 50 fms, green sandy mud (no. 99b) (1) ; off Salta Verde Point, 

 Santa Catalina Island, in 28 fms (no. 164a) (2) ; off Long Point, Santa 

 Catalina Island, in 19 fms (no. 224d) (3). 



Length of a large individual is 18.5 mm, width about 1.2 mm. The 

 body consists of 15 thoracic and 50 or more abdominal setigerous seg- 

 ments. Smaller specimens are about 13 mm long and 0.5 mm wide and 

 have fewer segments. The proboscis-like organ is a large, conspicuous, 

 ridged structure that extends far in front of the oral aperture (fig. 2). 

 On its ventral side (fig. 1) are 17 longitudinal ridges of uniform width 

 which continue around the sides so as to appear transverse on the dorsal 

 side. They are replaced abruptly by a broad series of dorsal stripes 

 (fig. 2). The mouth is visible as a transverse slit at the posterior mid- 

 dorsal position of the proboscis. Above it is an inconspicuous prostomial 

 region, giving rise on each side to a much larger three-lobed peristomial 

 part. This consists of a much folded medial part and a pair of large 

 lateral lobes (fig. 2). There are many slender tentacles inserted on the 

 large paired lappets on the side facing the branchiae. These tentacles 

 consist largely of slenderer subcylindrical processes that appear to be 

 transversely ridged, due to the presence of transverse rows of short ciliary 



'These numbers are published with ecological data in Hartman, 1955, p. 66. 



