tidae. Permocarboniferous (Uppermost Carboniferous and Lowermost Permian).
A. Suborder Pelycosauria
Family Sphenacodontidae (Pelycosauria). Carnivorous reptiles of from four to eight feet in length, with long, often very long, dorsal spines; three sacral vertebrae.
Sphenacodon Marsh, New Mexico. Dimetrodon Cope, Texas. Clepsydrops Cope, Illinois, Texas. Tetraceratops Matthew, Texas. Bathygnathus Leidy, Prince Edward Island.
B. Suborder Edaphosauria
Family Edaphosauridae (Edaphosauria). Subaquatic or terrestrial invertebrate feeding reptiles, from six to eight feet in length. Spines of dorsal vertebrae very long, each with transverse processes. Skull small, short, high, with numerous palatal and coronoid conical teeth.
Edaphosaurus Cope, Texas, New Mexico. Naosaurus Cope, Texas, New Mexico, Ohio, Germany, Russia.
C. Suborder Poliosauria
Family Poliosauridae. Lizard-like, insectivorous, four or five feet in length. Teeth conical; spines of vertebrae short; two sacral vertebrae. Texas and New Mexico.
Varanops Williston, Varanosaurus Broili, Poliosaurus Case, Poecilospondylus Case, Arribasaurus Williston, Scoliomus Williston and Case.
Family Ophiacodontidae. About six feet in length, carnivorous. Skull narrow; teeth slender and conical or flattened; temporal opening small, an upper one also in Ophiacodon; ribs holocephalous; limbs short and stout; two sacral vertebrae. Texas and New Mexico.
Ophiacodon Marsh, Theropleura Cope, Diopeus Cope, Secodontosaurus Williston.
D. Suborder Caesasauria
Family Caseidae (Caseasauria). Thickset, crawling and probably burrowing, invertebrate-feeding reptiles about four feet long. Skull
