Echinocyamidae
# Echinocyamidae

Echinocyamidae is a family of sand dollars. They are found mostly off the coast of Britain and Ireland and the North Sea, with scattered populations in the tropics.

## Description

They are Laganiformes with:

* simple radial internal buttresses along interambulacral margins;
* periproct close to peristome and opening bounded by first and second paired post-basicoronal interambulacral plates
* interambulacral zones terminating adaptively in one or two single small plates
* basicoronal circlet small and unspecialized
* no food grooves
