10 ON THE SYSTEMATIC POSITION OF HESPERORNIS. 
THE Penvic GIRDLE. 
The very close resemblance in general shape of the pelvis of Hesperor nis to that 
of Podiceps or Colymbus has been noted by Marsu. How close it is may be 
Fig. 11. Pertvis or HespERORNIS. 
= ~ We — 
a == : = ao << 2! 
Ls: Zay Te 
SSS 
‘\ y SSSs 
ONS 
S MR ATES 
4 = 
ie Vaaes 
ut 
N 
= 
Fig. 12. Penvis or Cotympus. 
expressed by saying that Marsu’s whole paragraph descriptive of the ilum of 
Hesperornis might be transferred to that of Colymbus, perhaps without the altera- 
tion of a word. 
The most striking character in the pelvis of Hesperornis is the want of 
any union between the posterior extremities of the ilium, ischium, and pubis. This 
is a common but not universal character in the Ratites as well as in the Tinamous ; 
at variance with it are the familiar facts of the pubic symphysis in Struthzo, the 
ischial symphysis in Rhea, and the union between ilium and ischium in Rhea and 
Casuarius galeatus. But apart from this matter, the general proportions of the parts 
are very strikingly different. The Ratite pelvis is remarkable, in comparison with 
all other birds, for the great relative development of the pre-acetabular part of 
the ilium. The pre-acetabular portion is as long, or very nearly so, as the post- 
acetabular, and is always the stronger, higher, and bulkier : in Apteryx and Dinornis 
the post-acetabular part of the bone is almost rudimentary. In Hesperornis we go 
quite to an opposite extreme, the pre-acetabular part being thin or weak, and little 
more than one-fourth of the entire extent of the bone; a similar relation holds in 
