PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 325 



mature birds its amalgamation with the leg-bone is complete, and not a 

 trace of its original existence remains. As it seems to be superadded 

 to the center which forms for the end of the shaft — an ossification found 

 pretty generally among all vertebrates with well-developed limbs — I 

 take it to be the homotype of the olecranon, and believe that Vicq- 

 d'Azyr and his adherents on the patella question could soon be led 

 to a similar conviction. This would be the more likely, as this old- 

 time anatomist, to whom we have referred it, would quickly discover 

 that we largely sided with him in a matter that still furnishes food 

 for argument in present times. I refer to the mooted point of tbe anti- 

 types of tbe bones of the extremities. Much has been written upon 

 this subject ; it has been well treated by Wyman in his paper " On the 

 Symmetry and Homology in Limbs " published in 1867. Three years 

 later Prof. Elliott Ooues ably handled the question of " Antero-posterior 

 symmetry, &c.," in a series of articles which appeared in the New York 

 Medical Record in 1870. Here I think the difference between what is 

 meant by homotypj^, or serial homology, and antitypy is most satisfac- 

 torily explained. Entirely opposite views in the premises are entertained 

 by Huxley and Flower, while those anatomists nearly agreeing with the 

 last-named were defended by Owen, thirty-four years ago, in his work 

 *' On the Nature of Limbs." The scope of this paper will not allow me 

 more than a simple expression of opinion, and this is to the effect that I 

 take the tibia to be the antitype of the ulna, as the fibula is of the radius. 

 There is no doubt about femur and humerus. It is almost unnecessary 

 to add, after what has been said above, that I regard the patella as a 

 sesamoid, and see the homotype of the olecranon in the tuberosity of 

 the tibia of the posterior extremity. 



Now, the patella in birds offers us some very interesting and varied 

 forms, notwithstanding the fact that anatomists often complain of the 

 lack of striking differences in the skeletons of this class. No doubt 

 there is much truth in all this, still we find marked departures from a 

 common type, when we come to group and exhibit together characters 

 from widely separated forms. 



Quite recently I had the pleasure of examining the leg-bones and pa- 

 tella of the type specimen of Aptenodytes pennantii used by Coues in 

 his paper on " Material for a Monograph of the Spheniscidte." (Proc. 

 Acad. Nat. Sci. Phila., xxiv, 1872.) I give you a life-size drawing of 

 these bones from the right limb of this Penguin, showing the great 

 quadrate patella slightly raised above its articulation with the tibia. 

 In the same cut, A and B, are copies of different views of the patella 

 of Eudyptes chrysocoine, by Morrison Watson (Eeport on the Sphenis- 

 cidce; Rep. Scien. Results of Exp. Voyage of H. M. S. Challenger, Vol. 

 vii, PI. vii, Figs. 9 and 10, Zoology, 1883). In the magnificent work I 

 refer to, Watson tells us that " the patella is of exceptionally large size, 

 and presents a somewhat peculiar form in the Penguins. In form it 



