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The movable scutum has its occludent margin considerably arched: the lower articular ridge is broader than the upper ridge, in which respect it resembles the same valve in V. laevigata, a South American form, but the whole valve is not so broad as in that species. There is no adductor ridge on the under surface. The movable tergum has its upper articular ridge narrow, and slightly produced into a point on the scutal margin: in this latter respect this species, also, resembles V. laevigata, but differs from it in the whole valve not being so broad in proportion to its height. /