90 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Antiplanes agamedea Dali, 1919 
Proceedings of the United States National Museum, 56:33; PI. 24, fig. 2. 
Shell small, white, covered with an olivaceous periostracum, with more 
than five whorls, apex eroded, the periphery with a rounded keel; spiral 
sculpture of a thickened flattish ridge in front of the channeled suture, and 
obscure spiral treading on the impressed anal fasciole and base, the canal 
smooth; axial sculpture of fine incremental lines more or less reticulating; 
the spirals and arcuate over the fasciole, the peripheral keel on the spire 
nearer the succeeding than the preceding suture; aperture elongate, the 
outer lip thin, smooth within, arcuately produced in front of the fasciole; 
inner lip erased, pillar short, solid, obliquely attenuated in front, straight. 
Height of four whorls, 10.5; of last whorl, 8; diameter, 5 mm. (Dali.) 
Type in United States National Museum, No. 211759. Type locality, 
Station 2936, off Cape San Quentin, Lower California. 
Range. Off Cape San Quentin in 359 fathoms. 
Genus BORSONELLA Dali, 1908 
Shell with a small, blunt nucleus of one or two whorls, sculpture chiefly 
spiral, feeble, except for one or two spiral carinae, sometimes with a few 
small riblets or beads on the principal carina; periostracum conspicuous, 
smooth or vermiculate; canal wide and very short; outer lip sharp, simple 
arcuate; pillar solid, with one strong, nearly horizontal plait continuous 
upon the whole axis; axis impervious, operculum absent. 
Type. Borsonclla dalli Arnold. 
Borsonella omphale Dali, 1919 
Plate 19, fig. 6 
Proceedings of the United States National Museum, 56:38; PI. 12, fig. 4. 
Shell slender, acute, with eight flattish whorls exclusive of the (lost) 
nucleus, white covered by a very light olive gray periostracum; suture 
distinct, fasciole hardly impressed; spiral sculpture of obscure striae, 
sparser on the base; axial sculpture of incremental faint lines arcuate on 
the anal fasciole; aperture narrow, anal sulcus wide, moderately deep; 
outer lip thin, prominently arcuate in front of the periphery; inner lip 
erased; pillar strong with a single fold near the body; attenuated in front; 
canal short. Height of shell, 16; of last whorl, 10; diameter, 6 mm, (Dali.) 
Type in United States National Museum, No. 209174. Type locality, 
Station 4309, off Point Loma, California. 
Range. Known only from the type locality. 
[90] 
