12 



is greater as compared to the transverse and vertical diameters. The pre- 

 orbital region is but little concave, and the anterior border of the orbit is 

 above the posterior half of the first true molar. The molar teeth present 

 a tubercle between the anterior lobes, and a weak cingulum extends round 

 the inner base of the anterior one, and in the second premolar, round the 

 base of both inner lobes. Thence it passes round the anterior base of the 

 crown and ceases in a tubercle which rises in contact with the anterior 

 median crest. On the posterior side of the crown the cingulum in like 

 manner terminates in the large three-sided posterior marginal tubercle. 

 The anterior median tubercle-crest is well distinguished from the anterior 

 inner tubercle and is directed very obliquely. The posterior median crest 

 is continuous with the inner, and is well separated from the external 

 crests. The external basal cingulum is robust, the columns are prominent, 

 and the outer faces of the external crescents deeply impressed but with a 

 well marked median ridge. The external cingulum and its margins is ru- 

 gose ; other parts of the enamel smooth. The first premolar has two 

 roots ; the second premolar is as long as the fourth, and longer than the 

 last true molar. 



Measurements. M 



Total length of cranium 280 



Length of dental series to first incisor 147 



" " " canine 130 



molar " .100 



" premolars 053 



" second premolar. 015 



Width of " " 015 



-r.. a . . , j antero-posterior 0135 



Diameter first true molar l 



t- transverse. 016o 



-.. e -. . , | antero-posterior .0135 



Diameter of last true molar l - m„n 



t transverse .-. .01 i0 



From A. conclonr Leidy, this species differs materially in the composi- 

 tion of the superior molars In that species there are no inner tubercle 

 and cingulum ; the anterior median crest is more completely separated ; the 

 anterior cingulum does not cease with the anterior marginal tubercle, and 

 the posterior marginal tubercle is linear, not trihedral. 



Anchitherium bkachtlophum, sp. nov. 



Portions of the maxillary bones supporting molar teeth, indicate a spe- 

 cies of the size of the A. equiceps, but differing in various respects. 



The median and inner tubercles are not deeply separated, and the for- 

 mer are cutoff from the external crescents by a deep fissure. There is no 

 tubercle between the bases of the inner cones, nor is there any internal 

 cingulum. The anterior cingulum does not develop a distinct tubercle, 

 and does not extend to the anterior extremity of the anterior outer cres- 

 cent. The posterior cingulum develops a large trihedral tubercle, and 

 then extends nearly to the external crescent. The external cingulum is 



