monopnoa

Century Dictionary and Cyclopedia

1. n. In Owen's classification, a “subclass of Reptilia,” containing all reptiles which breathe in one way only —that is, by lungs: distinguished from Dipnoa or Branchiotoca, which breathe in two ways —that is, either by gills first and lungs afterward in the case of the same individual, or some of them by gills and others by lungs. In this scheme, not easy to define satisfactorily. Prof. Owen makes his “class Reptilia” cover not only Reptilia in the usual sense, but also Amphibia or Batrachia. His Dipnoa are then conterminous with Amphibia proper. He divides Monopnoa into the orders Pterosauria, Dinosauria, Crocodilia, Chelonia, Lacertilia, Ophidia, Anomodontia, Sauropterygia, and Ichthyopterygia. Comp. Anat. Vert. (1868), III. 850.