174 



THE MERYCOIDODONTID/F. 



Mandible: The chin is slightly straighter than in M. cursor, the angle with the tooth row 

 being about 48°. It is also less concave. The condyle is less prominent, but the horizontal ramus is 

 somewhat deeper. The sigmoid notch is very shallow and the coronoid process short and light, while 

 the masseteric fossa is large. This fossa is narrow anteroposteriorly but is longer vertically than in 

 M. cursor. 



Foramina: The infraorbitals are above the interval between P 3 and P 4 . The supraorbitals are 

 small and rather near to the median suture. The foramen ovale is large. I do not find a foramen 

 rotundum. 



Fig. 125. — Merycoides latidens (Douglass). Skull and jaw. HT. 



(After Douglass, 1907.) 



Cat. No. 908 CM. 1/2 nat. size. 



Dentition: The teeth are moderately well worn. They are brachyodont with perhaps a slight 

 trend toward hypsodonty. The molar series are longer than the premolar (index 0.83). The pre- 

 molars are moderately quadrate. P 2 is much larger than P 1 and is set obliquely in the jaw, with the 

 front part situated anterointernally. The cingulum on P 2 almost forms a cusp posterointernally and 

 encloses a broad, shallow basin, while on P 3 this cusp is large. 



Skeleton: A few foot bones, found with the holotype, closely resemble those figured by Scott 

 as of Mesoreodon chelonyx. 



Merycoides longiceps (Douglass) 1907 

 Figs. 5, 126-128 



Original Reference: New merycoidodonts from the Miocene of Montana. Bull. Amer. Mus. Nat. 

 Hist., XXIII, Art. 32, pp. 809, 811-815, 822, figs. 1-5 {Mesoreodon longicefs). 



Type Locality: East side of North Boulder River, about six miles above the point where it empties into 

 the Jefferson River, near Cold Spring Post Office, Jefferson County, Montana. 



Geologic Horizon: Upper Miocene ("Beds . . . consist of fine buff-colored sands, which contain some 

 clay." The beds are stratified and dip westward toward the North Boulder River. A small horizontal section of 

 White River material lies between these Miocene beds and the Paleozoic limestone, according to Douglass). 



Type: Holotype, Cat. No. 9732 A.M.N.H., "a nearly complete skull with the mandible, the cervical, 

 lumbar, and sacral vertebras, portions of most of the dorsal vertebra;, a scapula, a pelvis, a femur, a tibia, a fibula, 

 a nearly complete hind limb including the foot, several other foot-bones, and many fragments." Collected by 

 Albert Thomson, 1902. 



