84 



osborn: OLIGOCENE, MIOCENE, PLIOCENE EQUID.E. 



Parahippus texanus Leidy 1868. 

 Plates 8.3, 9.10. Text Fig. 59. 



Anchippus texanus, Leidy, Joseph. "Notice of Some Remains of Extinct Pachyderms," Proc. Acad. Nat. Sci. Phila., Vol. XX, 1868, 

 pp. 231-232, no figure. "The Extinct Mammalian Fauna of Dakota and Nebraska," Jour. Acad. Nat. Sci. Phila., (2) Vol. VII, 1869, 

 pp. 312-313, PI. xxi, fig. 13. 



Horizon and locality. — (Leidy, Proc. 1868, p. 231.) " It was obtained from ' Hutehen's well,' from a yellow sandstone, 

 supposed to be of Miocene age, at a depth of 50 feet below the surface, in Washington County, Texas." Possibly Middle 

 Miocene. Name of collector not given. The Lower Miocene age of P. texanus is inferred from the referred specimens, 

 including an incomplete upper molar from the Upper Martin Canon beds, Logan County, Colorado, a stage belonging to the 

 upper division of the Lower Miocene, Merycochcerus zone (W. D. M. 1913). 



Type. — Acad. Nat. Sci. Phila. Coll. (Leidy, 1868) A portion of a superior molar tooth, m 1 or m 2 , lacking the outer 

 wall of the ectoloph. Measurements: (Gidley, 1907, p. 886) the measurements of the tooth are: anteroposterior 

 diameter, .019; transverse diameter .020+. 



Type figure. — Text Fig. 59 of this Memoir. 



Characters. — (Leidy, 1868, 1869, Osborn, 1918) (1) Ectoloph of same form as in Anchitherium; (2) inner lobes 



Fig. 59. Original figure of the type of Parahippus texanus Leidy, Acad. Nat. Sci. Phila. Coll., a portion of a superior 

 molar tooth, m 1 or m 2 , lacking the outer wall of the ectoloph. Natural size. After Leidy, 1869, PI. xxi, fig. 13. 



[protocone and hypocone] proportionately less robust; (3) median lobes [protoconule, metaconule] proportionately more 

 robust; (4) posteromedian lobe [metaloph] joining outer lobes [ectoloph]; (5) from middle of metaloph a process [crochet] 

 given off. (6) (Leidy, 1868, p. 232) " This process looks as if disposed to join the contiguous portion of the antero-median 

 lobe, together with it to form a crescentoid lobe, embracing the antero-external one, as in the corresponding columns of 

 equine teeth. No such arrangement exists in Anchitherium. [7] A triangular tubercle, as in the latter genus, occupies 

 the space at the back of the crown, and it appears as if its anterior angle had a disposition to join the contiguous portion 

 of the postero-median lobe [metaloph], to form with it a crescentoid lobe, in like manner as in the former case, to embrace 

 the postero-external lobe." (8) Strong anterointernal cingulum embracing protocone; (9) protoloph interrupted, uniting 

 with parastyle. 



Leidy's penetrating description of this fragmentary tooth, as largely emoted above in his own language, is prophetic 

 of the transition of the Parahippus into the Merychippus type of molar. As he observes in his final description (1869, 

 p. 313) "The tooth, from its structure, is evidently intermediate to those of Merychippus as a representative of the Equidm, 

 and those of Anchitherium." 



Referred specimen, Amer. Mus. 12924. 



