136 Bulletin American Mitseum of Natural History. [Vol. XIV, 



slender than in the larger varieties of E. caballus, (6) the lesser curvature of the 

 ribs near their heads indicates that the back was not nearly so wide, but shaped 

 more like that of the ass or zebra. (For description of skull characters see 

 American Museum Bulletin, 1900, Vol. XIII, Art. XIII, pp. 114-116.) 



Measurements given. 



_ . ^ , r « i Antero-posterior 33 mm. 



Diameters of crown 01 p^ - "^ 



( Transverse 31 



„. , , c , (Antero-posterior 32 " 



Diameters of crown of m- - ^ 



( Transverse 30 ' 



Long diameter of incisor 23 



Total length of molar-premolar series 190 " 



The type skull as well as the four other associated skulls in 

 hand when these measurements were given are all of young in- 

 dividuals that had not yet shed all their milk molars. Very 

 fortunately the writer has since collected a skull (No. 10628) 

 from the same deposit or quarry from which the others were taken, 

 in which all the teeth had come into full use (see PL XIX, Fig. A), 

 and the measurements can now be given more fully and more 

 accurately. They are as follows: 



T-,- . o ( Antero-posterior 43 mm. 



Diameters P^ •] tj • 



( Transverse 30. 5 ' ' 



Diameters p^ I ^"'^'■°-P°^'^"°^' 34 " 



( Transverse 33 " 



Diameters pAiAi^^e^-°-P°sterior 33 " 



( Transverse 33 " 



Diameters ml \ Antero-posterior 30 " 



( 1 ransverse 30 " 



Diameters m^-i^^^^^^-P"^*^"^'" 3i " 



( Transverse 29 " 



Diameters m^ \ Antero-posterior 31 " 



/ Transverse 24 " 



Long diameter of i^ 24 " 



Total length of molar-premolar series 204 " 



This species, which is intermediate in size between E..compli- 

 ■catus a.ndiE.pacificus, is distinguished from the former, especially, 

 by its comparatively longer muzzle, which equals in comparative 

 length that of E. caballus. From E. pacificus it is distinguished 

 by the comparatively smaller skeleton, the somewhat longer 

 muzzle, and by the different form of the occiput; that of E. 



