124: 



OHBORN: OLIGOCENE, MIOCENE, PLIOCENE EQUIDyE. 



Type. — U. S. Nat. Mus. 2572. (Cope, 1875, p. 259) "This three-toed horse is indicated by the oral and palatine 

 parts of the skull with the superior dental series of both sides, together with one mandibular ramus with all its teeth, 

 of an individual from near San Ildefonso; and also probably by molar teeth of two individuals from the Loup Fork 

 beds of Colorado." Measurements: (Cope, 1875, p. 260) superior premolar-molar series, p'-m 3 , .134; superior molars, 

 m 1 -!!! 3 , .062. 



Type figure. — Text Fig. 98 of this Memoir. 



Characters. — (Cope, 1875) (1) "The typical specimen belongs to an adult animal, and was taken from the matrix 



Fig. 98. Original figures of the type of Mcrychippus caJamarius Cope, U.S. Nat. Mus. 2572. (1) Palatal view, (la) 

 "external view of maxillary bone, containing three anterior molars of the left side" (Cope). Natural size. After Cope, 

 1877, PI. lxxv, figs. 1, la. 



by myself, without admixture of others." (2) Protocone column large, its centre anterior to the middle transverse line 

 of the crown, an angular projection toward the protoconule, actually connecting with the protoconule in m 2 ; (3) dentinal 

 band connecting the inner crescents [pi ml], giving off two or rarely one fold [double pli caballin] in the crochet region; 

 (4) borders of fossettes much plicate, anterior border of protoconule giving off from four to six folds; (4) posterior border 

 of postfossette exhibits one deep fold, which is generally bifurcated [hypostyle region]; (5) p 1 small, two-rooted; (6) no 

 basal cingulum on either jaw; (7) posterior molar, m 3 , smaller than the three preceding it. 



(Matthew, 1913) (8) Grinding teeth extremely long-crowned; (9) protocone separate to about one-third from base, 



