OSTEOLOGY OF BIRDS 



311 



the lower mandible ; and some of the ossifications of the sense organs 

 of Dendrocygna autumnalis with the corresponding parts 

 as they are found in the geese (Anser, Chen, and Branta) ; in 

 swans of the genus Olor, and in a 

 variety of species of ducks. Among 

 the ducks the skull of Dendrocygna 

 approaches most closely the teals and 

 the Mallard (Anas) ; and especially 

 does it come near the last named 

 fowl. But the skull of the Mallard 

 and the skull of the Trumpeter swan 

 (O . buccinator) are, apart 

 from the difference in size, almost 

 identically alike in character. In the 

 lower jaws of the geese I note that 

 the backward extending articular 

 processes are quite spiculiform and 

 but very moderately turned upward, 

 while in Dendrocygna in common 

 with Olor, mallards and teals (and 

 other ducks) these processes are 

 abruptly turned upward at right 

 angles, and although similarly flat- 

 tened from side to side, and markedly 

 broader from before, backward, ter- 

 minating, as usual, in a sharp point. 

 [Compare figures of skulls of Branta 

 and Spatula.] There is, however, 

 one very striking character in the 

 skull of Dendrocygna not possessed 

 by any other genus of anserine birds 

 with which I am at present ac- 

 quainted; and this is the meeting and 

 complete bony union of the apex of 

 the inferoposterior extending part of 

 the lacrymal and the distal extremity 

 oi the squamosal apophysis. This 

 condition completes the bony ring 

 surrounding either orbit, precisely as 



we see it in some parrots and a few other birds. The approach 

 towards each other of the tips of these processes is quite close in 

 either the Mallard or the Trumpeter swan, though always a con- 



Fig. 38 Superior view of the skull 

 of Branta canadensis. Man- 

 dible removed. Natural size. ^. 

 Same specimen as shown in figure 

 37. Drawn by the author 



