250 



OSTEOLOGY OF ANSERES. 



The vomer varies but little among the genera of this orde$ When 

 describing it for Mergus serrator it was said how its superior border 

 was finished off by a thickened rib. I find in an immature specimen of 

 Glaucionetta islandica that the most of this is contributed by the ascend- 

 ing processes of the palatine on either side, each sending a delicate 

 anterior process over the upper margin of the vomerine plate. In 

 mature skulls of Ducks and Geese the sutural traces of this condition 

 of affairs are obliterated, and from an examination of a skull of an adult 

 Duck we would be very much inclined to think that this thickened 

 upper rim of the vomer was a part of its own ossification. 



Fig. ?8. Skull of Br<in(a canadi nsix hutchinsii; 

 row above. Same specimen as Fig. 27: lit. 



Fir;. 29. Skull of Branta canadensis hutchinsii; 

 basal view with mandible removed; life size. 

 Same specimen as Figs. 27 and 28. 



Seen from behind (Fig. 30), we find the plane of the periphery of the 

 foramen magnum nearly at right angles with the basis-cranii, as in 

 Mergus ; but the chief feature that, strikes us here is, as already alluded 

 to, the great superiority of the Goose over the Merganser in its more 

 capacious brain-case, which, of course, is indicative of the possession 

 on the part of the former of a comparatively and correspondingly much 

 larger encephalic mass. 



In comparing the characters of the skull in Mergus serrator with the 

 corresponding ones as we find them in the majority of the Ducks, Swans, 

 and Geese, I find them to differ in the following general particulars: 



