226 Shufeldt, Osteology of Cereopsis nov(P-hollandics. \_iJ''\L\\ 



to the point where the postero-inferior angle of the ischium 

 abruptly sends down a broad process to meet it, the pubic element 

 is long and slender. At the point defined it is as much as three 

 or four times as broad, but contracts very gradually as it proceeds 

 backward towards its free end. where it moderately expands again 

 to form the dilation there existing. This expansion at the distal 

 free end of either pubic bone in Branta and Olor is conspicuously 

 large and paddle-shaped, while in Chen it is almost as we find it 

 in Cereopsis, the only difference being that, in the former, the 

 bone, after passing its articulation with the ischium, is more 

 abruptly curved downward. 



In all these genera there is a marked ischio-iliac notch on the 

 posterior pelvic border, which in Branta canadensis is converted 

 into a foramen by the ilium and ischium meeting behind it again. 

 (No. 17,980, Coll. U.S. Nat. Mus.) Sometimes, in Chen hyper- 

 horeiis, there is a minute foramen anterior to the notch on either 

 side that I have noticed in other pelves. 



In Chen ccerulescens the ischio-iliac notch is particularly deep 

 in some specimens. 



On the dorsal aspect of the pelvis, mesially, between the 

 acetabula, backward to a point about opposite the posterior 

 endings of the ischio-iliac foramina in Olor and Branta, the entire 

 area is much concaved, being deepest in the median line, and 

 rolling up on either hand above the antitrochanter anteriorly, 

 and the elongate, large ischio-ihac foramen, posteriorly. This 

 region is somewhat concaved in Cereopsis, but very much less so 

 in Chen, in which latter genus the iha are conspicuously separated 

 from the uro-sacral vertebrae, which is not the case in Branta, 

 and only in the case of the last two vertebrae in Olor colnmbianiis. 



Viewed ventrally, the pelvis in Cereopsis is very narrow and 

 contracted anteriorly, but broader, deep, and capacious after 

 passing the acetabula. This is more or less the case with all 

 these Swans and Geese, though in Olor colnmhianus — a very big 

 bird — ^the shortest distance between the ischio-ihac foramina 

 measures but 32 mm., while in Cereopsis — a much smaller fowl — 

 it measures 40 mm. 



In this Cape Barren Goose of Australia the skeleton of the 

 tail is not as well developed as it is in other anserine genera. The 

 four caudal vertehrce composing it have short, stumpy neural 

 processes with clubbed extremities, while the transverse processes 

 are short and depressed. Rudimentary, free chevron hones are 

 to be found between the last two or three of these vertebras, being 

 represented merely by twin ossicles resting on the transverse line 

 of the articulation between the centra of contiguous vertebrae. 

 Subquadrilateral in outline, the pygostyle is small for the size of 

 the bird, and in keeping with the vertebrae in advance of it. Its 

 upper border is sharp, while the lower one is thickened, longi- 

 tudinally grooved, and harbours three or four large pneumatic 

 foramina. 



This is also the case in Olor coUtmbiamis, in which bird the 



