CONDYLARTHRA. 493 



ular in section, their external sides forming a convex rib There is no nb 



between the external sides. There is a strong anterior cingulum, which 



terminates externally in a low angular cusp. Thei'e is no cingulum on any 



other part of the crown. The second, third, and fourth premolars have 



two external cusps, and much resemble the corresponding teeth in Hyraco- 



therium. The second is longer than wide, and has an internal ledge; the 



third is as wide as long, and has a wide internal ledge; the fourth is wider 



than long, and has an internal and two intermediate cusps, and an anterior 



and posterior cingulum. They all have a weak external cingulum, of 



which a trace exists in the true molars. 



The last inferior molar has a double anterior inner cusp, as in some 



Mesodonta, and the external anterior cusp is robust. All the cusps are 



conical and with round section, and their bases are close together. The 



outline of the base of the crown is almost an isosceles triangle with rather 



wide base in front. 



Measurements. 



M. 



Length of last six superior molars ^ .0350 



Length of true molars • 0160 



Diameters of M.ii^'*°*""P°*t^^''''^ «055 



t transverse 0080 



Long diameter base of Pni. ii 0050 



Diameters Pm. i;; ^ anteroposterior 0060 



( transverse 0060 



From the Wasatch beds of the Big Horn River, Wyoming; J. L. 



Wortman. 



MENISCOTHERIUiAl Cope. 



Eeport on Vertebrate Fossils from New Mexico; U. S. Geog. Geol. Survey W. of 100th Meridian, 1874, 

 p. 8. Report U. S. Geogr. Geolog. Survey W. of lOOtU Meridian, 1877, Vol. IV, Pt. II, p. 251. 

 American Naturalist, 18S2, p. 334. 



As already indicated, with this genus we enter a new family of the 

 Condylarthra, and one which superadds to its general structure a consider- 

 able specialization of the molar teeth. The present genus is the only one 

 of the family yet known, and it is represented by but three species. With 

 present knowledge it must be asserted that the range of this genus was 

 limited both in time and space. The remains of the species have been de- 

 rived from the Wasatch beds of New Mexico, and from a horizon from near 

 its base, which overlies the Puerco. The genus has not been found in any 



