4 ON THE SYSTEMATIC POSITION OF HESPERORNIS. 
Fig. 1. SkuLiL oF HESPERORNIS REGALIS. (After Marsu.) 
Fig. 2. Skutt or CoLtyMBUS SEPTENTRIONALIS. 
The vomer in Hesperornis is double. This is not the case in the Struthious 
birds ; but in the Colymbide and Podicipidee it is very deeply cleft behind, the two 
vomers being united for scarcely one-third of their length in Colymbus, while their 
posterior extremities are widely separate and help to keep the posterior ends of the 
palatines from contact with the basi-sphenoidal rostrum. 
To pass to the second of these points, MArsH gives no description in his text 
of the “strong ‘basi-pterygoid’ processes,” but they are figured (Pl. II.) in the 
posterior view of the skull. Now I know no bird’s skull in which these processes 
are visible in the rear-view: the process figured is a tubercle on the basi-occipital, 
far behind the pterygoid and the quadrate, which is well marked in Colymbus and 
Podiceps, but much better in the Vultures, the Geese, and many other birds, and 
which serves for the attachment of the inner portion of the digastric muscle. 
Fig. 3. Skutt or HEspERORNIS. Fig. 4. Skunn or ConyMBts. 
(Occipital view.) 
As regards the quadrate bone, we have shown elsewhere that it resembles in 
Marsu’s figure the quadrate of the Grebe to a considerable extent: and that it 
differs from a Ratite quadrate in every important feature ; in having, for instance, 
“a long, slender, well-formed shaft, a head whose two capitula are defined though 
not deeply cleft, a slender pointed (?) anterior process springing from the shaft at 
some distance from the head, a distinctly prominent pterygoid process, and a deep 
quadrato-jugal cup.” 
