EXPLAXATION OF PlATE 12 



Figs. 1-5. — Beringius beringi (Middendorff): 1, from 453 feet, showing a heavy shell with 

 long spire and relatively short aperture; 2, a juvenile, from 152 feet, just escaped from 

 the capsule; 3, a thinner shell, from 40 feet (Eluitkak. Pass, Aug. 10, 1948), with a 

 short spire and long aperture, shown with its operculum in place. 4, 5, young speci- 

 mens, from 125 and 216 feet, respective!}', showing variation in the nuclear whorls and 

 aperture. 



Fig. 6. — Beringius beringi var. kobelti Dal! from 125 feet. 



Fig. 7. — J'olutopsius stefanssoni Dall from 110 feet (Sept. 8, 1948). 



Fig. 8. — Natica clausa Broderip and Sowcrby from Eluitkak Pass (Aug. 6, 1948), shown 

 with its shelly opercuhmi. 



Fig. 9. — Polinices monteronus Dall from 295 feet, with its horn)' operculum, showing the 

 notched callus covering the umbilicus, and the thickened pillar lip. 



Fig. 10. — Polinices pallidus (Broderip and Sowerby) from 130 feet (Sept. 15, 1948). 



M.AGXIFICATIOX: All X .7. 



