 The enamel folds do not extend past the midlines of the molars.The mesoloph, an accessory crest on the upper molars that is usually well-developed in oryzomyines, is present but short on the first and second upper molar; it is much more reduced in "Holochilus" and "Pseudoryzomys".The corresponding structure on the lower molars, the mesolophid, is present on the first and second molars in "Lundomys", but absent in both "Holochilus" and "Pseudoryzomys".