Clinton R. Stauffer

“ A study of materials recently collected from the Detroit River series of Michigan and from the Onondaga limestone of Ontario has revealed numerous forms that cannot be identified with known species. Some of these are too fragmentary to be worthy of description, although the genera are easily determined. ”

“ The interior shows a strongly impressed muscular impression on the pedicle valve. This resembles very closely the similar impression in R. vanuxemi but differs from it in the conspicuous divisions characteristic of that species. In the species here described this muscular impression extends slightly more than half the length of the shell and is divided by a prominent median ridge. The brachial valve shows a slight rounded median ridge which extends about a third of the length of the shell and is continued backward into the cardinal process. ”

“ Arms more or less uniform in size, uniserial, long, and showing frequent bifurcations. These bifurcations are not uniformly spaced on the different arms and one arm does not branch within the limits of the preserved specimen. ”