PLIOHIPPUS. 



169 



Type. — Univ. Texas Coll. (cast 14393). (Cope, 1893, p. 67) "Three superior molars represent this species. 

 They were found at different localities in the neighborhood from which we obtained the teeth of the [Pliohippus] E. sim- 

 plicidens. . . .The species is named in honor of Mr. F. W. Cummins, who has done so much for the geology and paleon- 

 tology of Texas." Of these isolated molars, belonging to different animals and found in different localities, the best 

 preserved may be taken as the type. Measurements: (Cope) a.p. .024, tr. .024, length of crown .033. This fractured 

 tooth is the left superior molar represented in Plate XX, Fig. 7. One of the paratypes is represented in Plate XXIII, 

 Fig. 1. 



Type figure. — Text Fig. 135 of this Memoir. 



Characters. — (Cope, 1893, p. 67) (1) Of smaller size than the type of Pliohippus simplicidens. (2) Enamel borders 

 of fossettes entirely simple [due to extreme wear]; (3) prominent convexity of the internal wall of the paracone and 

 metacone, from which it results that the external enamel border of each fossette is deeply concave [convex]; (4) proto- 

 cone with a short anteroposterior diameter as in P. simplicidens, not bilobate or grooved on the internal face; (5) an 

 angle of the posterior border of the prefossette represents the loop [crochet fold] ; (6) cylindric character of paracone and 

 metacone. 



8 



Pliohippus minutus 



Fig. 136. Type of Pliohippus minutus Cope, Univ. Texas Coll. (cast Amer. Mus. 14392), ?ni2 of the right side. 

 (Left) Original figures of the type. After Cope, 1893, PI. xx, (8) crown view, (8a) internal view, (8b) external view. 

 (Right) Type tooth, crown, (a) external, and (b) internal views, new drawings. All figures natural size. 



Gidley (1907) observes that this type shows affinities either to Protohippus or Pliohippus; also that the greater depth 

 of the notch anterior to the protocone suggests a somewhat more advanced form than any species of Protohippus from 

 the Miocene horizon. 



Pliohippus minutus Cope 1893. 

 Plate 33.8. Text Fig. 136. 



Equus minutus, sp. nov., Cope, Cope, Edw. D. "A Preliminary Report on the Vertebrate Paleontology of the Llano Estacado," 

 Fourth Ann. Rept. Geol. Surv. Texas, (1892) 1S93, pp. 67-68, PI. xx, fig. 8. 



The term Equus phlcccjon Hay was proposed (Bull. U. S. Geol. Surv. No. 159, 1901) to replace the term Equus minutus 

 Cope, which is preoccupied. 



Horizon and locality. (Cope, p. 67) "... from near the middle of the series from Mount Blanco." Crosby County, 

 Texas. Middle Pliocene. Name of collector not given. 



