190 BULLETIN FLORIDA STATE MUSEUM Vol. 18, No. 3

gasy Republic, characterized by a hinge at the anterior lobe of the plastron. GEOLOGIC RANGE.-No known. GEOGRAPHIC RANGE.-Malagasy Republic. REMARKS.-Relationships not clear. Only one species recognized, P. arachnoides. REFERENCES.-Skeleton: Gray 1873c, Williams 1950b.

Genus tStylemys Leidy Stylemys Leidy 19 5 1a, p. 173 (not of Maack 1869). Leidy 1851a, p. 173. Leidy 1851b, p. 173. Auffenberg 1963, p. 87 (part). Brattstrom 1961, p. 547 (part). GENOTYPE.-Stylemys nebrascensis Leidy. DEFINITION.-An extinct Holarctic of characterized by a premaxillary ridge; a symphyseal dentary groove; pleurals only slightly alternately narrower and wider laterally; moderately long un- specialized tail with some vertebrae lacking interpostzygopophyseal notches; posterior epiplastral excavation shallower or absent; no hinge on plastron or carapace; pleural bones not, or only slightly differen- tiated; free proximal portion of ribs long; a single supracaudal scute; nuchal scute longer than wide. The most recent description is that by Auffenberg (1964d). Glaessner (1933) discussed the general problem of "stylemiform" tortoises. GEOLOGIC RANGE.- to Miocene of North America, Miocene of Europe and Oligocene of Turkestan, U.S.S.R. GEOGRAPHIC RANGE.-United States (Oregon, California, Nebraska, Colorado, South Dakota, Utah, Texas), France, and Turkestan. REMARKS.-Shells described as Stylemys bottii from the Miocene of France (Stefano 1902a) and Stylemys karakolensis from the Oligocene of Turkestan (Riabinin 1927) may belong to this genus and are provision- ally placed here.

Stylemys amphithorax (Cope) Testudo amphithorax Cope 1873a, p. 6. Stylemys amphithorax Auffenberg 1962d, p. 9. Geochelone amphithorax Auffenberg 1963, p. 81 (in error). TYPE.-American Museum of Natural History; cotypes, various parts of three shells. TYPE LOCALITY AND HORIZON.-Head of Horsetail Creek, Weld County, Colorado, U.S.A.; Horsetail Creek Member, White River Forma- tion, Chadronian faunal age, Early Oligocene.