ON THE SYSTEMATIC POSITION OF HESPERORNIS. 13 
The inter-orbital fenestra is very large, as in Colymbus, not very small as 
in the Ratites. 
The basi-pterygoid processes, which, arising from the body of the basi- 
sphenoid bone, are conspicuous in the Ratites, have not been demons- 
trated to exist in Hesperornis and are entirely absent in Colymbus. 
The vomer is double in Hesperornis, and is so deeply cleft as to be nearly 
so in Colymbus ; but it is short and single in the Ratites. 
The pterygoid has two articular surfaces for contact with the quadrate as 
in Colymbus, not one only as in the Ratites. 
The occipital condyle is large, cordate, and very prominent, as in Colym- 
bus; not small and low as in the Ratites. 
The ex-occipital region, as in Colymbus, sends down no broad descending 
process as it does in the Ratites. 
The squamosal, as in Colymbus, sends down no descending process to 
overlap the quadrate as it does in the Ratites. 
The lachrymal bone was apparently small, narrow, and bent, as in Colym- 
bus ; not large, flattened, and curved as in the Ratites. 
The nostrils are holorhinal, as in Colymbus; but their character is quite 
different in the Ratites. 
The premaxillaries are deeply excavated at their sides for the anterior 
nares, as in Colymbus; they are not excavated at all in the Ratites. 
The mandible is prolonged backwards at its angle, as in Colymbus, not ~ 
bevelled off or truncated as in the Ratites. 
The quadrate has a head which is almost certainly divided into two 
capitula to as great an extent as in Colymbus: its anterior process is 
long and slender as in Colymbus, not short, thick, and truncated as 
in the Ratites: its quadrato-jugal cup is deep and well-defined as in 
Colymbus, not imperfect or rudimentary as in the Ratites: its ptery- 
goid process is distinct and prominent as in Colymbus, and not 
ill-defined or absent as in the Ratites. 
The axis vertebra in Hesperornis 
Was as large as the third vertebra, as it is also in Colymbus, not small 
compared with it as in the Ratites. 
It had, like Colymbus, no lateral foramen or canal, such as is present in 
the Ratites. 
It appears to have had a thin, sharp hemal spine, which in Colymbus also 
is thin, sharp, and long, but is absent or rudimentary in the Ratites. 
The other characters drawn from the vertebral column need not be further 
recapitulated here. 
