546 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



vol. 48. 



tance is 170 mm. Where the ilium is narrowest the diameters are 

 34 mm. and 20 mm. In E. hemionus the corresponding diameters are 

 32 mm. and 17 mm. The distance from the middle of the superior 

 border of the acetabulum, measured along the axis of the ilium, to the 

 anterior border is almost exactly the same in the two species, 187 mm. 



In E. francisci the pubic border continues forward as a sharp 

 ridge much further than it does in E. hemionus, in which it disap- 

 pears at a point about 50 mm. in front of the acetabulum. As the 

 hinder portion of the acetabulum is missing the diameter of this 

 can not be determined. The left pubis as preserved appears to reach 

 the symphysis, and there is also a fragment of the right one. The 

 distance from the symphysis in a straight line to the outside of the 

 acetabulum is 106 mm., the same as in E. hemionus. The anterior 

 border is sharper than in the latter animal, while that part which 

 forms the anterior boundary of the ischio-pubic foramen is nearly 

 flat. The section of the pubis at this point is thus triangular. 



The size of the ischio-pubic foramen can not be determined, but 

 it must have been much larger than in E. hemionus, where the 

 greater diameter is only about 40 mm. In the Texas horse it could 

 hardly have been less than 60 mm. It is further evident that the 

 ischium extended backward a considerably less distance than in 

 E. hemionus. In the latter the distance from the hindermost border 

 of the ischio-pubic foramen to the hinder border of the ischium, 

 measured 20 mm. from the symphysis, is 110 mm. ; in E. francisci the 

 distance is 75 mm., but this diminution is partly due to the greater 

 size of the foramen. The ischial tuberosities are missing in the 

 Texas specimen. In Equus hemionus the thickness of the bone be- 

 tween the two foramina is 25 mm. ; in E. francisci about 10 mm. 



The right femur is represented by the head and trochanters and 

 by that part of the distal end which bears the articular surface for 

 the patella. Of the left femur there are present the head and a part 

 of the great trochanter, a portion of the shaft, and the inner half 

 of the distal end. The latter part is broken into two pieces, one 

 being the condyle, the other the tuberosity for the support of the 

 patella. 



Measurements of the femur in millimeters. 



E. 



francisci. 



E. 

 hemionus. 



Arabian. 



Length of the femur, total 



Length of the femur from head to distal end, inner side 



Diameter through head and great trochanter 



Diameter of head, fore and aft 



Greatest traverse diameter at middle of length 



Greatest side to side diameter at distal end 



Diameter of inner condyle, side to side 



Diameter of outer condyle, side to side 



Greatest side-to-side diameter through ridges bounding groove for 

 patella 



91 



48 

 ±50 



27 



26 



53 



342 

 308 

 98 

 48 

 46 

 81 

 30 

 28 



52 



425 



380 



120 



61 



47 



100 



37 



35 



64 



