The Laganiformes are generally smaller, rounded, flat sand dollars. The Laganidae (still extant) are best represented in the Indo-Pacific, while the fossil species in the Neolaganidae were found from the Eocene to Miocene in the southeastern U.S. and the Caribbean. An additional fossil genus, Pentedium from Eocene Georgia, is considered a sister to the neolaganids (Kier 1968). Of the U.S. neolaganids, the Durhamella species and Neolaganum durhami were associated with pure sand substrates, while Weisbordella and Wythella were associated with more muddy substrates (Carter et al. 1989).
