ANSERES 



467 



pterygoids are placed so far forwards that the anterior ends 

 of those bones articulate with them. 



Fig. 224. — Skull of Qtoerquedula crecca. Lateral View. 



(After Huxley.) 



Fr^ frontal ; iVa, nasal ; Pmx, premaxilla ; Fo, vomer ; Pa, palatine : Pt, pterygoid. 



The vomer is a thin deepish plate of hone which is more 

 or less jintimately connected with the 

 median septum and maxillo-palatines in 

 front. The maxillo-palatines are com- 

 pletely fused across the middle line in 

 many Anseres (e.g. Chen, HymenolcBmus) ; 

 in Biziura and Mergus they come into' 

 contact but are not fused. The latter 

 has very un-ducklike palatine in that the 

 somewhat delicate maxillo-palatines diverge 

 from each other after their junction pos- 

 teriorly as well as anteriorly, the palatine 

 vacuity in front being (for a duck) un- 

 usually extensive. In Chen ccerulescens, 

 indeed, secondary bony growths have 

 almost completely obliterated this vacuity, 

 a kind of ' false ' palate having been 

 formed. 



The lacrymal bones are large, having 

 a considerable length of line of union with 

 the skull ; they are sometimes (e.g. Chloe- 

 phaga) and sometimes not (e.g. Mergus) 

 ankylosed with the orbital margin. Ccrc- 

 ■opsis has (among the genera which I have examined) a skull 



Fig. 225. — Vektkal 

 View of Same. 



Mccp, maxillo-palatines. 

 Other letters as in fig. 224. 



