336 M. R. Thorpe — A New Merycoidodon. 



These rami were collected by H. B. Sargent, former Yale 

 Corporation member, on the Yale College Scientific 

 Expedition of 1870; another specimen, Cat. No. 12586, 

 Y. P. M., collected by Sargent at Gerry's ranch, Colorado, 

 is a very robust individual with an unusually great 

 bizygomatic diameter. It would seem to represent the 

 male, but sex dimorphism is almost impossible to deter- 

 mine in this genus. Cat. No. 12471/2, Y. P. M., from 

 Nebraska, shows a quite large style developed from the 

 cingulum between the protocone and hypocone of both 

 M^; Cat. No. 12094, Y. P. M., is a skull with a well 

 developed single-rooted accessory premolar between C 

 and P^ on both sides. The muzzle is elongated and both 

 P^ are set obliquely. This extra premolar is probably 

 comparable to that found occasionally in the long-muzzled 

 species of Canis. There is a certain degree of variation 

 in the depth but not in the extent of the lacrymal fossa, 

 which may be due to sex, those skulls having the more 

 shallow fossa possibly being the females. The length of 

 the superior molar-premolar series varies from 80 to 

 90 mm. ; the molar series ranges from 45 to 50 mm., and 

 the premolar from 37 to 42 mm. 



Another specimen. Cat. No. 12101, Y. P. M., from the 

 Middle Oligocene of White River, Nebraska, appears to 

 be intermediate between M. culbertsonii and Eporeodon 

 hyhridiis in its proportions. The cranium is broken away 

 so that the presence or absence of the bullae can not 

 be determined. The muzzle is quite wide beneath the 

 orbits and the infra-orbital foramen is above the middle 

 of P^. The length of the molar series is 49 mm., that of 

 the premolars 45 mm., while the width beneath the orbits 

 is 101 mm. 



The Yale Expedition of 1914 collected several bones, 

 including the skull and jaws, of an individual of this 

 species (Cat. No. 12238, Y. P. M.), on the Warbqnnet 

 ranch, 12 miles north of Harrison, Nebraska. * The 

 enveloping matrix as typical Middle Oligocene. The 

 various elements are normal, except possibly the pes, 

 which is very excellently preserved and articulated. On 

 the ventral surface of this, close to metatarsal II, was 

 found in the matrix a small elongate bone which appar- 

 ently represents the hallux. This bone is 17.5 mm. long, 

 although the proximal end is somewhat damaged. The 



