188r.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 217 



apex ; the lower margin is sharp, and above it is convex, except in the 

 cranio-facial region and somewhat beyond, where it is depressed. 



A nasal is a large, broad bone; its anterior margin is rounded as in 

 other holorhinal birds. Tbe nostril is elliptical and placed horizontally, 

 and the sutural traces of the bones that surround it entirely obliterated. 

 A lacrymal bone is triangular in form, its apex below terminating in a 

 spindle-form process, which is curved somewhat outward. Along its 

 superior border it anchyloses with the frontal and nasal, the sutural 

 trace being quite distinct in the adult skull. Not so, however, in most 

 of the Ducks and Geese. 



All anserine birds seem to possess a slender jugal bar; in the case 

 of the Red-breasted Merganser, its distal end turns abruptly upward 

 to make its articulation with the quadrate. 



This latter bone has its orbital process widely bifid ; its mastoidal 

 head is single and roundly convex. 



Fig. 1. Skull of Mevnuis serrator 



;ht lateral view; life size. By the author, from specimen 16626, 

 Smithsonian collection. 



The facets at its mandibular foot are two in number, placed obliquely. 

 They differ considerably in form and position from the same parts as 

 seen in a specimen of a Brant before me. 



The sphenotic process is prominent and gradually curves downward 

 along its extent. In most Ducks it points downward and forward. 



We find the hinder moiety of the superior orbital periphery rounded 

 off for the lodgment of the nasal gland. The extent to which this is 

 carried varies in the different species of anserine fowl. 



About the center of the interorbital septum there occurs a large fenes- 

 tra, and the foramina for the exit of the first and second pair of nerves 

 are much larger than necessary for this purpose alone. 



The pars plana is a very thin, curved sheet of bone, which supports 

 in front a crumpled mass of equally attenuated osseous tissue. This 

 latter projects into the upper space of the rhinal chamber, and no 

 doubt plays the part of a turbinated bone. Neither of these outgrowths 

 come in contact with the inner aspect of the lachrymal bone of the same 

 side. 



The lower margin of the rostrum is straight, rising gently upward 

 as it is projected forward, being sharp below along its anterior moiety. 



