OSTEOLOGY OF BIRDS 



257 



Both in form and position (or articulation) the palatines and 

 pterygoids of the Hooded merganser (Lophodytes cucul- 

 1 a t u s ) apparently agree with M . serrator. 



The basitemporal region is broad and smooth, and a spinelike 

 process at its apex fails to shut out from view the double orifice 

 leading to the Eustachian tubes. 



We find the major portion of the crota- 

 phyte fossa upon the lateral aspect of the 

 skull. Still it may be seen also from a pos- 

 terior view, where the two depressions ap- 

 proach each other, but are separated by a 

 large domelike, supraoccipital prominence. 



This latter is usually pierced by an irregu- 

 lar foramen on either side, which is quite 

 characteristic but not always present in the 

 ducks and geese, and are small even in Loph- 

 odytes. In a specimen of Branta cana- 

 densis hutchinsii before me a large 

 cue occurs only on the left side of the promi- 

 nence. 



M-ergus has a large foramen magnum which 

 faces almost directly backward. The occipital 

 condyle at its lower margin is of a reniform 

 outline with the notch above. 



In the mandible the symphysis is short, and 

 this bone,' when seen from a superior aspect, 

 is of an acute V-shape form. 



The anterior two thirds of either ramus is 

 narrow, tapering somewhat to the front, with 

 both upper and lower borders rounded. On 

 the outer surface a deep, median, and longi- 

 tudinal groove of hairlike proportion is drawn 

 along- its entire length. 



The hinder third is much wider, nearly 

 double the width, and, instead of being thick 

 like the forepart of the bone, is a vertical 

 lamelliform plate. Its border is sharp above, 



while below it is rounded, being in the same ^author; same specimen as 

 line with the inferior border of the anterior shown in figure 1 

 two thirds. 



The ramal fenestra is nearly or quite closed in by the surround 

 ing elements; a long, oblique slit marks its site. A curved projec 



Fig. 2 Skull of Mergus 

 serrator; viewed from 

 above, mandible removed; 

 natural s ; ze. Drawn by the 



