OSTEOLOGY OF BIRDS 275 



The supraorbital glandular depressions for the nasal glands, so 

 prominent in many of the auks and other waterfowl, are here in 

 the Anatinae rarely well marked. 



In Spatula they consist in a very narrow trimming off of the 

 edge of the orbital peripheries, barely perceptible in the Mallard 

 and Nettion Caroline n sis. In Clangula they are better 

 developed, but in this duck they are really moved down so as to 

 form one of the features of the lateral aspect of the skull. They 

 are quite well marked in the Hutchins goose. 



Spatula, Anas p 1 a t y r h y n c h o s , and the teals have a 

 strongly incised notch on either side, at the anterior arc of the 

 supraorbital rim, which seems to define the posterior ending of the 

 lacrymal bone. It is absent in the Garrot, but again characteristic in 

 swans and geese. 



The vault of the cranium behind is, upon this aspect, usually 

 smooth and rounded. A longitudinal crease may pass it in the 

 middle line, and elevations on either side in some forms (Spatula, 

 Olor) faintly indicate the divisions of the encephalon within. It 

 is indented in Oidemia perspicillata, and uniformly 

 smooth and rounded in Mareca. 



Turning now to the under view of the skull of Spatula, we 

 are to note the great concavity of the premaxillary, with its sharply 

 defined parial gutters for vessels and nerves and their ramifications. 



As is well known, all 'the Anatidae exhibit the typical desmog- 

 nathous arrangement of the palatal bones. The maxillopalatines 

 unite in the middle line to form a larg'e bony mass (rn.vp), in front 

 of which there occurs in most all the Chenomorphae, that I have 

 been enabled to examine, a more or less cleanly cut elliptical open- 

 ing, the remnants of a much greater vacuity in other birds. It is 

 very perfect in M a r i 1 a v a 1 1 i s n e r i a. , in Polysticta, and 

 in other forms, while it is narrow and pointed posteriorly in O . 

 perspicillata. In the swans these maxillopalatines are quite 

 spongy ;in Branta canadensis hutch i n s i i they unite 

 with a firm lamelliform nasal septum that makes a long abutment 

 against the roof of the rhinal chamber above. This nasal septum 

 is entirely absent in Spatula, and illy developed in N e 1 1 i o n car- 

 ol i n e n s i s and the Mallard. 



In Spatula, the palatines (pi) (and the arrangement, with a few 

 unimportant minor differences, holds good for the group) are 

 horizontally compressed at their anterior ends, where they form 

 anchylosed schindylesial articulations with the premaxilla and max- 



