OSTEOLOGY OF BIRDS 



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rate just mentioned above. Apart from such trivial characters as 

 these, however, and the completed orbital rings, the skull of 

 Dendrocygna autumnalis might answer for any ordi- 

 nary duck of the genus Anas, and does in reality essentially repeat 

 the characters as found in the skull of such a species as the com- 

 mon Mallard. And, as has already been said above, the skeleton of 

 the lower jaw of Dendrocygna, apart from the difference in size 

 (or rather in length), is absolutely identical in character when 

 compared with the mandible of the duck just named. The differ- 

 ence in length amounts to 1.5 centimeters in favor of the Mallard. 

 At the present writing I have but few skulls of foreign geese at 

 hand, but among these occur specimens ( ? male and female) of 

 the species known as Chloephaga poliocephala of the 



Fig. 41 Right lateral view of the skull of Chloephaga poliocephala. J 1 . 

 Drawn natural size by the author from a specimen collected in the Strait of Magellan 

 by Thomas H. Streets, United States Navy. I, lacrymal; mxp, maxillopalatine; v, 

 vomer; pi, palatine; pt, pterygoid 



Straits of Magellan. In general form these skulls differ consider- 

 ably from the skulls of our Bernicla or Branta, as they are now 

 known, and rather seem to slightly approach the skulls of some 

 of the ducks in certain characteristics. 



Viewed from above, we find the supraorbital glandular depres- 

 sions unusually well marked for an anserine bird, and they are 

 separated in the median line by about 3 millimeters; being rather 

 more than this in the female specimen. 



A lacrymal bone has, in each- instance, almost completely an- 

 chylosed with the frontal and nasal of the same side; and at the 

 lower extremity of this bone we find an ossicle similar in every 

 respect to the one I described as occurring in the skull of L a r u s 

 argentatus. This little bone shows well in the figure, extend- 

 ing backward from the lower expanded portion of the lacrymal. 



