1898.] Osboni, Evolution of the Amblypoda. Part I. 



215 



tional interest (Fig. 28). Associated lower tooth fragments, put 

 together by Dr. Matthew, resemble those of a small Coryphodon, 

 and clearly separate this animal from Bathyopsis. The differ- 

 ences from the pes of Coryphodon are very significant, as follows : 



1. Navicular laterally reduced, excluded from cuboid by ectocuneiform, a 

 unique condition. 



2. Ectocuneiform enlarged, articulating with astragalus (unique). 



3. Second or middle phalanges greatly abbreviated upon all digits, I-V, 

 as in Uintatherium manus. 



4. Front surface of astragalus widened, separating tibial and navicular facets 

 as in Uiniat/ierittm . 



5. Tibia long and slender, unlike Coryphodon. 



The measurements of the metatarsals are as follows : 



Mts. 1 = 22. Mts. 11=42. Mts. 111=48. Mts. IV=42. Mts. V=34. 

 Other measurements in Table on page 199. 



Fig. 28. Coryphodon singiilaris. Superior and lateral views of pes. Am. Mus. Coll. 

 No. 2980. 



This animal thus shows one progressive character (4), two 

 entirely unique and distinctive characters (i, 2) ; the latter, 

 together with (5), sharply separate it from Coryphodon ; two char- 

 acters, 3, 4, parallel or approach Uintixtheriiim. The other Wind 

 River species, C. zvortmani and C. ventaniis, are distinguished 

 from this by their typical metapodials, one of which is known 

 in each type. 



The associated femur (No. 2970) is proportioned like the tibia, 

 long and slender. 



