2.J2 . NEW YORK STATE MUSEUM 



Mobility of the craniofacial hinge, however, does not seem to 

 depend upon this condition, for in Clangula, where a consider- 

 able amount is enjoyed, this individualization of the nasal processes 

 of the premaxilla does not obtain *to such a marked extent. 



Passing to other members of this group, we find the general 

 characters exhibited on the part of the superior osseous mandible to 

 be more or less uniform. It is universally elongated ; thin ; markedly 

 convexed above, and correspondingly concaved upon its ventral 

 aspect, with a sharp cultrate edge all around. Anteriorly it is 

 rounded off, never coming to a point at that extremity. 



In some ducks it is short and wide, as in Marila affinis; 

 in others it is narrow and proportionately elongated as in Dafila, 

 and particularly in Mareca americana; while in others, as 

 in most of the scoters, it is both long and wide, besides being more 

 or less lofty. In some of these latter birds there is often a bony 

 bulbous enlargement observed, upon either side, in the region of 

 the nasal bones. These osseous bullae are enormously developed 

 in the Surf scoter (Oidemia perspicillata). In this form, 

 they are ellipsoidal in outline, either one being nearly as big as the 

 cranium, with smooth external surface. Laterally, they bulge con- 

 spicuously out in the nasal region ; meet in the median line in- 

 ';ernally, where the maxillopalatines usually occur; while the two 

 argely fill the rhinal chamber. These enlargements appear to me 

 o be the remarkably swelled maxillopalatines themselves, which, 

 ipon either side, externally, are closely overlaid by the nasal bone, 

 he latter being greatly pushed outward from its usual position, and 

 n the adult, indistinguishably fused with the peculiar enlargement 

 n question. I can at present see no special use that these swellings 

 ;an be to the Surf scoter, unless it be to give a greater surface 

 Externally, over which are spread the highly colored integuments, 

 :hat may be an object of admiration in the eyes of the females of 

 .his species. The dorsal line of the culmen in this duck is convex 

 Dver the narial openings, and descending or concave in front of 

 .hem, a very uncommon character in the group. 



Confining ourselves for the present to the lateral aspect of the 

 skull, we find a notorious anatine character very pronounced in 

 Spatula, and this is the enormous development of the lacrymal (/) 

 and the consequent anteroextension of the lacrymofrontal region. 



The descending process of this bone reaches backward toward the 

 long sphenotic apophysis, nearly to touch it in Clangula, in which 

 duck it usually lacks the terminal dilation so prominent in our sub- 



