328 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



The relative proportions of these structures, however, differ very 

 much in Podiceps and Colymhiis. The patella in Podiceps probably 

 contains actually more bone, that is to say, it is larger than the rotular 

 process of the tibia; whereas in Colymbus, the rotular i)roces8 of the 



Fig. 3. — Leg-bones and patella from Podiceps cor- 

 nutum. F, the limb rotated slightly outwards. 

 G, a square lateral view. In the first the bones 

 are in situ ; in the second, femur and patella 

 thrown backwards out of position. Lettering 

 as before, with a rotular crest of tibia. No. 

 1120, Army Med. Mus., life size. Drawn by the 

 author from the specimen. 



Fig. 4. — Colymbus septentrinnaUs ; life size; let- 

 tering as in former figures. (Spec. 16628 Smith- 

 sonian collection.) Bv the author. 



tibia is a very extensive prolongation upwards of the shaft, while the 

 j>atella is reduced to a diminutive flake of bone, articulating above the 

 base on its posterior aspect. This is well shown in my drawing of these 

 parts, taken from a si^ecimen of Colymbus septentrionaUs (Fig. 4). 



The Loon, as another representative of the same genus, shows a like 

 condition or arrangement of the structures involved, and we are all fa- 

 miliar with the illustration, now so long on duty, given us by Professor 

 Owen in the second volume of his Anatomy and Physiology of Ver- 

 tebrates. In passing it may be as well to call attention to the fact, 



