[8] Didymictis had an elongated and relatively large skull with small and low braincase and a long and narrow basicranial region.

The authors concluded that Didymictis was a relatively specialized terrestrial carnivore capable of hunting with speed or pursuing by digging.

[11] Cope assigned his specimen, "one entire and a portion of the other mandibular ramus, with teeth well preserved", to the creodont genus Limnocyon and named his new species L.

[1] D. proteus is known from the late Paleocene and earliest Eocene of Wyoming and the only species present in the Tiffanian and Clarkforkian stages.

[11] D. vancleveae is known from a fragmented jaw with several teeth (Colorado) described by Robinson in 1966 and another tooth (Wyoming) tentatively assigned to this species.