Vol. 6] Miller: Condor-like Vultures of Bancho La Brea. 



L3 



also are raised slightly higher. Details of comparison show 

 the differences to be quite marked. 



Viewed from in front, the shaft is excavated at the head end in a 

 deep pit enclosed on all sides by abrupt walls. Even in the region of the 

 attachment of the tibialis antieus this depression is completely leveed 

 and the anterior furrow of the tarsus passes down the shaft on a plane 

 much less deeply placed than the floor of the proximal depression. This 

 anterior furrow extends less than half way down the tarsus. At its 

 middle point the shaft is not concave from side to side. In the Recent 

 form the whole anterior face is occupied by a broad depression, abrupt 

 at its proximal end, only slightly interrupted by the insertion of the 

 tibialis antieus and passing almost insensibly into the groove leading into 

 the foramen for the adductor tendon of the outer toe. The outer border 

 of the furrow in the fossil form gradually merges into a well-defined ridge 

 which becomes most noticeable at the middle portion of the shaft. Thence 

 it is deflected outward and skirts the border of the foramen of the 

 adductor of the external digit. In the Recent form no such ridge is 

 visible. The narrowness of the shaft and the fact that the transverse 

 diameter is nearly constant for so great a part of the length, makes the 

 curvature very abrupt at either end where the bone widens for its articu- 

 lations. This is especially noticeable in case of the inner profile at the 

 proximal end. 



Seen from the side the greater thickness of the shaft is at once notice- 

 able. The trochleae are larger. The greater thickness of the head is quite 

 apparent as is the greater size of the intercotylar tuberosity. The 

 attachment of the articular ligaments is raised into more of a tubercle. 

 The hypotarsus is slightly higher on the shaft. 



Seen from the rear, the narrowness of the shaft is again evident. The 

 longitudinal limiting ridges are thrust toward each other in the middle 

 portion. The median ridge coming down the shaft from the hypotarsus 

 curves over to the inner side until it makes a line concave from without. 

 The facet of the accessory metacarpal is placed relatively higher up the 

 shaft. The lateral toes are likewise placed higher. The hypotarsus is 

 set off less abruptly from the general plane of the bone. 



Seen from without, this latter feature becomes evident in the head region 

 by the less marked concavity in the region of the internal proximal foramen. 

 In Gymnogyps the bone is very thin in this region and the internal lon- 

 gitudinal ridge of the shaft passes up fully to the tarsal head. 



A scrutiny of the facets of tibial articulation brings out very markedly 

 the distinction between the two forms. The two facets in Sarcorhamphus 

 clarM are almost equal in size and both are longest in their antero- 

 posterior axes. In Gymnogyps calif ornianus, the outer facet is longest in 

 its transverse axis while the inner is longest in a line at nearly forty-five 

 degrees with the sagittal plane. The depression between the articular 

 surfaces just back of the tubercle is not so deep, so narrow nor so obliquely 

 distorted in 8. clarM. The transverse furrow separating the hypotarsus 

 from the head is not so deep nor so well defined in the fossil form. 



