188 



Am eric ail Se ash ells 



smooth and narrowly channeled. Shell smooth, yellowish white and covered 

 with a thin, yellowish brown periostracum which flakes off when dry. Um- 

 bilicus absent or a very slight slit. Operculum paucispiral, horny, translucent- 

 brown and with microscopic, spiral lines. A moderately common, cold-water 

 species found just offshore down to 70 fathoms. 



Its counterpart, A. purpurea Dall, common in Alaska, is very similar, but 

 % inch in length and with a greenish and darker periostracum. 



Oldroyd's Fragile Moon-slieli 



Figure 4^^- 



Genus Eunaticina Fischer 1885 

 Eunaticina oldroydi Dall 



Oregon to San Diego, California. 



1/4 to iVi inches in length, resembling Lunatia leivisi, but much lighter 

 in weight, with a more pointed spire, without the heavy, brownish callus and 

 having, instead, the upper part of the columella expanded into a white, thin 

 area which partially obscures the umbilicus. Micro-sculpturing on shell exte- 

 rior is prominent. Moderately common; dredged offshore 30 to 70 fathoms. 



Figure 43. a, Polifiices draconis Dall, 2 inches (Pacific Coast); b, Natica clausa 



Bred, and Sby., i inch (Arctic waters); c, Jjiimtia pallida Bred, and Sby., 1^-2 



inches (Arctic waters); d, Lamellaria diegoensis Dall, Y^ irich ( Calif oi-nia); e, 



Eunaticina oldroydi Dall, 2 inches (Pacific Coast). 



