SKELETOIv' OF THE MUSK-DUCK. 397 



nasal process of the premaxilla. The descending process forms 

 a linguiform plate apposed to tlie outer surface of the maxilla. 

 This bone differs from the typical nasal in that the descending 

 process is placed at right angles, instead of obliquely, to the pre- 

 maxillary process (PI. 39. fig. 1). 



The premaxilla is unusually short and very broad ; its extreme 

 tip has been broken off. The inferior surface of this bone is 

 unusually dense, and is not pierced by foramina as is usually the 

 case among the Anatida?. The aperture of the anterior nares is 

 of great size. 



The maxilla, partly on account of the relatively small size ot 

 the premaxilla, is very largely exposed. The palatine processes 

 are oblong in shape, of considerable size, and, in this specimen, 

 touch one another in the middle line by their postero-internal 

 angles, leaving a large palatine vacuity. The maxillary antrum is 

 shallow. 



The quadrato-jugal bar recalls that of the Mergansers and of 

 Somatetna, in that it turns abruptly upwards to articulate with 

 the quadrate. This is due to the fact that the glenoid cavity or 

 the quadrato-jugal has shifted so as to be nearer the squamosal 

 head of the quadrate. 



The lachrymal is free and triangular in form, having the 

 descending process long, slender, and curved backwards. The 

 orbital and nasal processes are not well-defined, blending 

 insensibly with the descending process : the orbital process 

 bears a small tubercle near its free end. 



The frontals are extremely narrow in the orbital region and 

 bear shallow grooves facing outwards from the supra-orbital 

 gland. Anteriorly they are widely separated so as to expose 

 the mesethmoid when the nasal processes of the premaxilla are 

 raised. 



The parietal region of the skull — the frouto-parietal suture 

 can no longer be distinguished — is long and bounded posteriorly 

 b}^ a narrow and well-defined " temporal fossa," which is con- 

 tinued downwards along the paroccipital process. 



The supra-occipital is pierced by a small fontanelle, such as is 

 usually met with in the Anatidae. 



The postorlital process differs conspicuously from that of the 

 typical Duck, and resembles that of the Mergansers in that it is 

 short and directed downwards. In the normal Ducks this process 

 is of considerable length and directed downwards and forwards. 



28" 



