1888 ] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 235 



The lower margin of the vomer is sharp, and the whole plate is gently 

 I arched in such a manner as to make the upper edge convex along its 

 continuity, the reverse obtaining below. 



When speaking of the palatines I neglected to invite attention to the 

 notch found on the inner margin of either one of them about opposite 

 the anterior termination of tbe vomerine plate. This notch is converted 

 into a foramen in the Mallard, and entirely absent in Hutchin's Goose 

 and the Whistling Swan. 



Spatula possesses a pterygoid (pt) of the same general form it assumes 

 in any of the Anatidce. Its shaft is short and straight, while its anterior 

 end is much enlarged, first, by a descending lamina of bone developed 

 upon it and, secondly, by the large sessile, elliptical facet on its oppo- 

 site side for articulation with a similar facet on the sphenoidal rostrum. 

 Anterior to this facet the pterygoid develops an upturned process of 

 spine like dimensions, which, when the bones are in situ, is closely ap- 

 plied to the back side of the ascending process of the palatine. Below 

 this process the pterygoid is deeply and roundly notched to receive a 

 peg-like projection on the palatine, which movably fits into it. 



The projecting and rounded posteroexternal angle of the palatine 

 extends below this pterygoidal articulation. 



Generally the lower border of the rostrum is rounded; it is very 

 broadly so in Brant, though it becomes quite fiat in Glaucionetta ; there 

 it may be carried forward as a projecting process. 



The anterior ethmoidal edge is always sharp, sloping forward and 

 upward to become a median crest on the under side of that part of the 

 . bone which abuts against the frontal region for its entire length. 



In Spatula the basitemporal region is quite broad, and marked by a 

 median and rounded ridge. This is carried out upon the pointed lip of 

 bone that under-laps the double entrance of the Eustachian tubes in 

 front. A decided dimple is found in front of the sessile and superiorly 

 notched occipital condyle, while the foramen magnum is large, of a 

 cordate outline, with its apex directed upward. 



Laterally we find the descending temporal wings, with the usual 

 group of foramina to the inner side of each, at the base of quite a well- 

 marked little fossa. 



The plane of the foramen magnum makes an angle of about 4o° with 

 the backwardly produced plane of the basis crauii. 



A posterior aspect of the skull of this Duck (Fig. IS) shows a con- 

 spicuous supraoscipital prominence, with a large, vertical, and ellip- 

 tical foramen opening into the cranial casket on either side of it. The 

 occipital area is well divided off from the crotaphyte fossae by a raised 

 ridge which surrounds it. These last-named depressions are separated 

 in the median line by quite an extensive interval. I believe they never 

 meet in any true Duck. 



This description of the cranial base and posterior aspect of the skull 



