302 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
Mopalia ciliata elevata Pilsbry, 1892 
Tryon and Pilsbry, Manual of Conchology, 14:300; PI. 64, figs. 82, 83. 
More elevated, acutely carinated, more or less pitted superficially, and 
either painted with the pattern of typical lignos on a white, creamy, or 
green ground, or having concentric zigzag blackish streaks. Divergence 
about 90°. The interior is bright green or blue. (Tryon and Pilsbry, Man¬ 
ual of Conchology .) 
Type in Philadelphia Academy of Natural Sciences. Type locality, 
Puget Sound? 
Range. Forrester Island, Alaska, to Puget Sound. 
Described as Mopalia lignosa form elevata Pilsbry. 
Basiliochiton lobium Berry, 1925 
Proceedings, Philadelphia Academy of Natural Sciences, 77:28-9; PI. 11, figs. 1-2. 
Shell rather small, with a slight luster; elongate-oval, well-elevated, 
the side-slopes nearly straight; valves distinctly beaked behind. Entire 
surface unsculptured and nearly smooth except for the numerous very fine 
lines of growth and traces of an extremely minute granulation barely 
discernible under even high magnifications. Texture of shell somewhat 
streaky radially. 
Anterior valve short, crescentic, its slope very steep in front and 
slightly convex; faint traces of low radial ribs leading to the insertion 
slits possibly discernible. Intermediate valves with lateral areas scarcely 
definable and not raised. Posterior valve small, with well-elevated median 
mucro, and an initially sharply falling, then more gradual slope behind. 
Articulamentum subtranslucent, porcellaneous, whitish. Sutural laminae 
thin, rather broadly arcuate, not continuous across the fairly wide, dis¬ 
tinctly spongy sinus. Specimen not disarticulated, but anterior valve evi¬ 
dently with about 8 intermediate valves with 1-1, posterior valve with 9 
slits, all slits having porous rays leading into them, which are especially 
conspicuous in the head valve. Girdle narrow, rather delicate and inclined 
to curl in dried material; covered dorsally with very minute granular 
scales, giving an effect like fine sandpaper, and an abundant, but easily 
broken, marginal armature of long, dagger-like spinelets; a few similar 
spinelets noted here and there on the upper surface may be adventitious 
from the margin; sutural tufts present, consisting of a group of 3-12 
somewhat falciform spinules situated on whitish spots a little way out 
from each suture, 7 rather smaller tufts around the head valve, and 5 
similar ones around the tail valve; best preserved tufts indicative that these 
are remnants of coarsely spinulose, recurved, plume-like setae, bearing 
[904] 
