Deltidium Sentence Examples

The ventral valve is usually the larger, and in many genera, such as Terebratula and Rhynchonella, has a prominent beak or umbo, with a circular or otherwise shaped foramen at or near its extremity, partly bounded by one or two plates, termed a deltidium.

These plates are secreted by the ventral lobe of the mantle, and were named by von Buch in 1834 the " deltidium."

The form of the deltidium varies in different genera.

The American use of the term deltidium for the structure which Europeans call the pseudo-deltidium makes for confusion.