†Chlorostoma (Omphalius) dalli subnodosus Arnold 1907 (top snail)
Gastropoda - Trochoidea - Trochidae
Full reference: R. Arnold. 1907. New and characteristic species of fossil mollusks from the oil-bearing Tertiary formations of southern California. Proceedings of the United States National Museum 32(1545):525-546
Belongs to Chlorostoma (Omphalius) dalli according to R. Arnold 1907
Sister taxon: Chlorostoma (Omphalius) dalli inornatus
Type specimen: USNM 161985
Ecology: epifaunal grazer
Distribution: found only at Head of Topanga Canyon (Arnold 1907) (Miocene of California)