Morphological correlates of food choice and habitat use in earthworms developed on Lumbricidae and some New Zealand Megascolecidae applied in a general sense to some North American species of the genus Diplocardia (Megascolecidae), but use of the same criteria between taxa is not valid. Intestinal infolding was less extensive in the Diplocardia than in the Lumbricidae, but species of both groups that feed below ground had the greatest development of dorsal infolding of the intestine. The Diplocardia species present in North American prairie included one topsoil-surface feeding species and four species that feed below ground on unrecognizable organic matter, with infrequent root and leaf fragments