268 NEW YORK STATE MUSEUM 



The femur has a very large head, which rises somewhat above 

 the broad articular summit of the shaft, notwithstanding its crown 

 is considerably excavated for the ligamentum teres. The axis of 

 its neck makes an angle with the axis of the shaft. 



Trochanter major is suppressed above, while on the anterior 

 aspect its thin edge partly surrounds a sort of fossa, where in other 

 birds the pneumatic orifices occur. Its shaft is rather compressed 

 from side to side and bent very slightly in the anterior direction. 

 About its middle, on the posterior aspect, there is a prominent 

 muscular tuberosity, and other lines or scars for muscular inser- 

 tion are evident. Of the condyles the outer one is the lower, and 

 it is profoundly cleft for the fibular head. 



The popliteal depression is represented by a characteristic conical 

 pocket just above the internal condyle on the posterior aspect. The 

 rotular channel in front is also deep, but does not extend up the 

 shaft a great distance. 



The patella of this merganser is seen to consist of two segments, 

 with an oblique groove in the cartilage connecting them. Through 

 this the tendon of the ambiens muscle passes. 1 



Tibiotarsus has a straight shaft that, unlike the femur above it, 

 is somewhat compressed from before backward. At its proximal 

 extremity we find a cnemial process reared above its articular sur- 

 face for the femur. Prominent cnemial ridges occupy the anterior 

 aspect of this, as usual. Of these the procnemial ridge is the higher 

 and extends the lower on the inner side of the shaft. 



The distal end of tibiotarsus presents nothing peculiar. The 

 groove anteriorly is deep, and the osseous bridge that spans it is 

 thrown directly across. The external condyle is the broader in 

 front, and its outer aspect is in the same plane with the side of the 

 shaft, while the corresponding surface of the inner condyle lies be- 

 yond the plane of the shaft, for its own side. 



Behind these condyles still continue to be parallel to each other, 

 but separated by an intercondyloid concavity that from its shallow- 

 ness is scarcely worthy of the name, while the condyles themselves 

 really merge into a broad, articular surface in this locality. 



The fibula, when articulated, is found to rise above the summit 

 of the tibia and project beyond it posteriorly. ' Its head is com- 

 pressed from side to side, which gives it a very short, transverse 

 diameter, while its anteroposterior one is fully three times as long. 



1 Shufeldt, R. W. Concerning Some of the Forms Assumed by the Patella in Birds. 

 U. S. Nat. Mus. Proc. 1884. 7:324-31. See figure 2, D, giving the knee of Mergus 

 senator and showing this patella [ U. S. Nat. Mus. Collec. spec. 16626]. 



