265 NEW YORK STATE MUSEUM 



Each preacetabular portion of an ilium is much shorter than its 

 postacetabular part, and also on a very much lower level. In front 

 its border is emarginated, transversely truncate, and somewhat ser- 

 rated. The surface of the bone is concave, and for the most part 

 looks upward and outward. 



Behind the acetabulum most of the ilium is devoted to the lateral 

 aspect of the pelvis. 



Turning to this side of the bone, we notice a propubis of con- 

 siderable size in front of the cotyloid ring, while the postpubic 

 element is a long slender rod, extending directly between the under 

 side of the obturator foramen and the posteroexternal angle of the 

 ischium, with which it articulates. Beyond this, it trebles its width 

 and curves rather abruptly toward its fellow of the opposite side. 

 A very narrow, open strait connects the obturator foramen and 

 the obturator space ; the former being rather smaller than usual 

 and the latter very large. 



The lower margin of the ischium is concave downward and very 

 sharp, while the posterior border of the pelvis, formed by both 

 the ischium and ilium, is perpendicular to the long axis of the bone. 

 It shows one or two indentations that are not to be found in the 

 same pelvic border of the eider. 



The acetabulum is large, with its inner and outer rings nearly 

 of the same size ; an antitrochanter of moderate dimensions stands 

 between it and the anterosuperior margin of the large elliptical 

 ischiac foramen. 



Posterior to this latter aperture the ilium rises as a smooth dome 

 above its own posterolateral plane and the ischium which lies below 

 it. 



In the present specimen this convexity shows a large fenestra 

 in either ilium at its anterior part. No such vacuity exists in the 

 eider or in other ducks in my possession, nor is it present upon 

 either side in the pelvis of Lophodytes which I have at hand. In 

 some specimens, however, the bone in the same locality is so thin 

 that I expect it occasionally occurs in those birds also. The pelvis 

 in Lophodytes is proportionately very much shorter than it is in 

 Mergus, and in not a few particulars it departs but slightly from 

 the pelvis as found in certain ducks. Spatula clypeata, for 

 example. The small propubis, the narrow obturator space, the far 

 broader posteroinferior angles of the ischia, are characters all more 

 ducklike than they are typically mergine. 



As already stated there are seven free caudal vertebrae and a 

 pygostyle. The neural canal passes through all of the former and 



