152 THE MERYCOIDODONTID/E 



border nearly straight, and angle unimportant; infraorbital foramen over M 1 to above interval 

 between M 1 and M 2 . 



Dentition: Teeth hypsodont. P 1 simple; P 2 and P 3 with posterior crescent larger than anterior 

 and median crest moderately weak; P 4 with no pit in anteroexternal corner. Index: 0.71 to 0.78. 

 M 3 about a fifth shorter than M 1 and M 2 . Inferior premolars compressed and narrow; Pi usually 

 oblique; P 3 without intermediate crests, anterior portion simple, and posterior part enclosing a 

 simple basin; M 3 longer than Mi and M 2 in the genoholotype. Indices: 0.70 to 0.72. 



Skeleton: Limbs short and stocky as a rule, but those of M. matthewi slenderer and more 

 delicate. 



Etymology: Merycochcerus (ruminant + hog). 



Species: 



M. buwaldi Merriam 1919. 



M. ccenopus Scott 1890. 



M. magtms Loomis 1924. 



M. matthewi Loomis 1924. 



M. proprius Leidy 1858. Genotype. 



Merycochcerus buwaldi Merriam 1919 

 Fig. 112 



Original Reference: Tertiary mammalian faunas of the Mohave Desert. Bull. Dept. Geol. Univ. 

 Calif., XI, pp. 507-511, figs. 84-88 (Merycochcerus ? buwaldi). 



Type Locality: South limb of the Barstow syncline, north of Barstow, California. Univ. Calif. Coll. 

 Loc. No. 2057, about 1000 feet below the top of the beds in the Barstow syncline. 



Geologic Horizon: Upper Miocene (Barstow). 



Types: Holotype, Cat. No. 21350 U.C.M., superior dentition in a small portion of a skull. Paratypes: 

 Cat. No. 21485 U.C.M., part of skull and fragment of mandible, both with teeth; Cat. No. 21354 U.C.M., 

 inferior last three premolars; and Cat. No. 21487 U.C.M., fragmentary mandible, with incomplete molars. 

 Named in honor of Professor John P. Buwalda. 



Specific Characters: A complete skull is unknown, but the total length is probably upwards 

 of a foot. The anterior part of the zygomatic peduncle arises above M 1 . In advance of the peduncle 

 the maxillary is somewhat flattened in a plane nearly parallel with the palate. 



Mandible: This has approximately the Merycochcerus form. It is high anteriorly, and one 

 mandibular fragment indicates that the depth increases rather rapidly below the posterior molars, 

 though not to such a degree as in Pronomotherium. 



Foramina: The infraorbitals lie above the anterior half of M'~. 



Dentition: The teeth are hypsodont. The length of the molar series is considerably greater 

 than that of the premolar series. There is some specialization and crowding in the anterior 

 premolars. 



Superior: The incisors are very small, and the canine is typically triangular. There is an 

 internal basal cingulum on the premolars. The long axis of P 1 is oblique to the sagittal plane of 

 the skull. In P 2 there is no small anterior excavation, such as appears in the P 2 of M. proprius, and 

 the anterior and posterior crescents are more nearly equal in size. The posterior crescent of P 3 is 

 relatively much smaller than in the genoholotype. The anterior and posterior styles on P 3 and P 4 

 are possibly a little better developed than on those of the type species, and so are the weak median 

 vertical ribs on P 2 and P 3 . The molars are apparently more hypsodont than in M. proprius. There 

 are suggestions of ribs on the external surfaces of the paracone and metacone, and the internal 

 cingulum is very faint or absent. The mesostyles are not rolled forward to the same degree, nor is 



