28 SHUFELDT — OSTEOLOGY OF THE CUCKOOS. [Jan. 4, 



rather small. A shallow excavation upon its upper side marks the 

 usual point for the. insertion of the round ligament. 



The subcylindrical shaft faintly showing the muscular lines is 

 considerably bent to the front, and at its distal extremity in that 

 situation the rotular channel is well marked, the condylar ridges 

 bounding it being about parallel to each other. 



The outer and larger condyle of the two is at the same time the 

 lower, and the fibular cleft that marks its posterior aspect is very 

 wide and deeply sculpt, being rather more to the outer side than is 

 usual. 



Above these condyles, behind, the popliteal fossa is but mod- 

 erately excavated, and a straight transverse line bounding it below 

 divides it from the general trochlear surface. 



We find in the next segment of this limb, the tibio-tarsus with a 

 subcylindrical shaft below its fibular ridge that is slightly bent so 

 as to be in the vertical line, somewhat convex anteriorly. The 

 bending here though is not nearly so great as we find it to be in the 

 humerus and femur or, to make the comparison more exact, in the 

 ulna. 



The cnemial crest of this leg-bone is but little raised above the 

 undulating articular surface of its summit, while the pro- and ecto- 

 cnemial ridges that develop below it are not peculiar. 



Their planes are not at right angles to each other, that of the latter 

 having its surface facing directly to the front. Neither is produced 

 for any distance down the shaft of the bone, but they terminate 

 rather abruptly upon it ; the procnemial ridge terminates at a point 

 about opposite the superior end of the fibular ridge on the other 

 side of the shaft.. 



At the distal extremity of the tibio-tarsus the planes of the con- 

 dyles are nearly parallel to each other, and these trochlear eminences 

 are strikingly close together in Geococcyx. 



The intercondyloid fossa is deeply excavated in front, to become 

 suddenly much shallower behind as well as somewhat narrower. 

 Upon lateral view it will be seen that the general outline of either 

 of the condyles is more circular than we usually find it in others of 

 the Class, where a reniform pattern prevails. 



Just above the condyles, on the anterior aspect, the vertical 

 tendinal channel is spanned by the usual little oblique bridge of 

 bone, and this is supplemented in life by a longer ligamentous one 

 placed in front of it. 



