394 DE. R. W. SHUPELDT ON 



Professor Owen evidently considered the smal, scale-like bone 

 found in the tendon of the extensor femoris, at its insertion, 

 to be the patella in that bird. When I first examined this 

 question, this was likewise my opinion, and in a paper on the 

 patellfe in birds, published in 1884 in the ' Proceedings of the 

 United States National Museum,' I so figured it (fig. 4, p. 328) 

 for C'olymhus septentrionalis {Gavia stellata). This opinion was to 

 some extent qualified later on, when I stated, with respect to the 

 Loons (" Urinatoridae ") that they possess "only a very small, 

 flake-like sesamoid, which occurs in the tendon of the extensor 

 femoris muscle at its insertion, and probably the true patella has 

 coossified in the adult with the elongated cnemial process of the 

 tibio-tarsus"*. Possibly some avian osteologist has published on 

 this subject, but if so, I have not seen the work ; and never 

 having been so fortunate myself as to have come into possession 

 of the skeleton of any Loon, secu.red at the right time to demon- 

 strate the exact composition of the tibio-tarsus in that bird, I am 

 still in doubt on the question. However, it is quite possible — 

 indeed quite likely — that the true patella in Loons [Gavia) is, in 

 the adult, completely coossified with the great elongate cnemial 

 process of their tibio-tarsi. The moulding of the patella on the 

 back of this process in Grebes, especially in very old birds, is 

 wonderfully close, — so close in some ligamentous preparations as 

 to deceive the eye upon casual examination. 



To settle this interesting point — if it has not as yet been 

 settled — will require the examinations of the skeletons of Loons 

 including those of individuals of the genus of all ages. 



At present I am inclined to think that the patella in Gavia, 

 in the adult, has been indistinguishably fused with the cnemial 

 process of the tibio-tarsus, for the reason that it is on the road to 

 such a fate in the Grebes (Colymbidse), and that in all such birds 

 as Hesperornis — an ancient ancestor of the Loons — the Penguins, 

 the Cormorants, and some others, the patella is very large. 



Then, finding it large in a Grebe, one would naturally look for 

 the same in such forms as Loons, especially when one considers 

 the relationship of these two families. 



The statements now being made are, in a way, prefatory, leading 

 up to what I have to say on the patella of the Cormorants. It 

 must be borne in mind in this connection that the patella in 

 Penguins is very large, and grooved obliquely across the anterior 

 face for the tendon of the ambiens muscle t. 



* "Concerning the Taxonomy of the North Amevican Pygopodes based upon their 

 Osteology," Jour. Anat. & Phys. London, .Jan. 1892, pp. l'99-203. The lines quoted 

 are from page 202. In this paper I also give two figures of the skeleton of the thigh 

 and leg of a Grebe, in which the patella is included. One of these figures was repro- 

 duced by Coups in his fifth edition of the ' Kev,' without acknowledgment (vol. ii, 

 p. 1052, fig. 712). 



t Cones, E. " Material for a Monograph of the SpheniscidiE," Proc. Acad. Nat, 

 Sci. Phila. xxiv. 1872. 



Watson, Morrison. " Anatomy of the SpheniscidiE " (Rep. Scient. Eesults of 

 Vovage of H.M.vS. ' Challena-er,' Zoology, vol. vii. pi. vii. figs. 9 & 10, 1883). 



Shufeldt, R. W. Proc. U.S. Nat. Mus. 1884, p. 326, fig. 1. Reproduces from Watson 

 figures of patelltE of Aptenodytes pennant i I and JSiidi/ptes chrysoeome. Comments 



