The three genera (or generic terms) that serve for the title of this paper comprise a series of Cretaceous and Tertiary Echinoids which are morphologically similar, and, in consequence, systematically chaotic. Although the time is not yet ripe for an attempt to disentangle the nomenclature of the various genera and species from the knot in which it is involved (a condition not to be wondered at in view of the early description and variable qualities of the forms), it seems desirable to publish the following comments on the group, making use of current names for the examples quoted. Pyrina, Desmoulius, as Lambert has shown, is typified by P. pelrocoriensis, Desm., a species that might well pass for a young member of the Conulus series. Conulus, Leske, has for genotype C. albogalerus, Leske, and the forms to which that name is usually applied in this country seem sufficiently like the original figure to pass muster. The genotype of Echinonëus is of course E. cyclostomus, Leske, and there has never been serious confusion as to the application of the generic name.