Sentence Examples with the word Avicula

The fossils from the Rhaetic beds belong to the Avicula contorta zone, those from the Lias to the Ammonites angulatus zone, while the blocks of limestone with chert contain Inoceramus, Cretaceous foraminifera and other organisms. The materials yielding these fossils are embedded in a course volcanic agglomerate which gives rise to crags and is pierced by acid and basic igneous ricks.

Rudimentary cephalic eyes occur in the Mytilidae and in Avicula at the base of the first filament of the inner gill, each consisting of a I pigmented epithelial fossa containing a cuticular lens.