236 OSTEOLOGY OF ANSERES. 



in the Spoon-bill practically answers for the Mallard and the Teals, 

 though, of course. Blight differences do exist. 



In Qlaucionetta islandica the basis crauii is proportionately flatter ; 

 the temporal wings less manifest; a separate ridge bounds the fossa 

 for the nerve and arterial foramina externally, and the condyle is more 

 prominent and its superior median notch very deep. The vault of the 

 cranium is very lofty in this Duck (Fig. 19), and the ridge bounding 

 the occipital area almost crest-like. 



Speaking of the unusual height of the cranial vault in the Garrot, we 

 find this bird very peculiarly constructed in this particular, for not only 

 is the brain case of a size 1 above the average for the group, but a curious 

 and nor inconsiderable diploic cavity overlies the whole top of the skull, 

 extending as far forward as the mesethmoid. Here it is interrupted by 

 a pair on either side, one in front of the other, of deep and sharply de- 

 fined chambers, with their apertures facing directly downward. This 

 condition is not so pronounced in a young female Glaucionctta, a speci- 

 men of which T Lave before me. 



Urania has a very large brain-case, and upon the under side of the 

 skull of a specimen of B. canadensis hutchinsii we note that a quadrate 

 has an area of no mean size, and nearly horizontal, extending to the 

 rear of its mandibular facets. In this Goose, too, we find a very broad 

 and Hat basi temporal area, with the shield to the entrance of the Eu- 

 stachian tubes nearly aborted. These latter appertures are wide apart 

 at the situation usually protected by it. The temporal wings are feebly 

 developed in comparison with the Cygnince, and the occipital condyle is 

 almost pedunculated. The group of foramina to its inner side of either 

 temporal wing is situate at the base of a well-defined fossa specially 

 designed to receive them. 



Finally, we observe that the form of the foramen magnum is more 

 elliptical in outline rather than cordate, as we found it in the Ducks. 

 Above it the supraoccipital prominence is very conspicuous, while the 

 foramina on either side of it may or may not exist. 



In the skull taken from a magnificent male specimen of Olor colurn- 

 bianus* I find the basi-temporal triangle comparatively very small, with 

 the dimple anterior to the condyle deep and having parial ones placed 

 side by side in front of it. The descending temporal wings are enor- 

 mously developed, each one overshadowing a considerable excavation 

 to its inner side. 



The condyle is relatively smaller than it is in the Geese, and its supe- 

 rior notch not so well marked, while the foramen magnum is quite cir- 

 cular in outline. Elliptical vacuities mayor may not exist at the sides 



* I am greatlj indebted t<> fche generosity of Mr. <;. Frean Morcom, of Chicago, for 

 this present. The bird was forwarded tonic by Mr. Morcom from Chicago to Fort 

 Wingate, N.Mex., by express. It arrived in excellent condition in the flesh, and the 

 line skeleton it a Horded me has been of the greatest service in the present connection. 

 When this memoir is published it is my intention to present the specimen to the 

 Smithsonian Institution at Washington as a type. — R.W.S. 



