77 Hesperornis, Shufeldt 



in great detail in the "Odontornithes." 



Between the firs-t and the ninth tooth on either side - the 

 most anterior tooth being considered the first - the median por- 

 tion of the premaxillary has an average width or transverse dia- 

 meter of one centimeter; and, as the mesial margins of the pre- 

 palatines (pp) are somewhat further apart than this -though 

 they approach each other anteriorly and posteriorly - a long spin- 

 dle-shaped hiatus results upon either side of the premaxillary. 



These hiatuses are also to be observed in Marsh's Fig. 5 of 

 Plate I of the "Odontornithes," where they have precisely the 

 same positions and apertural extent. In this figure, too, we have 

 the point indicated, upon either side, where the maxillary (mx) 

 gradually commences to broaden. This is as it is in most Colym- 

 bid<z and Gaviida, and in all probability is quite correct. 



Posterior to these maxillary expansions we have the remainder 

 of the quadrato-jugal bar upon either side ( j-qj) ; and, as we have 

 the posterior or quadro-J?ig-al portions of these, there can beno doubt 

 but that the jugal extension forward, to join the maxillary in the 

 case of either bar, was as we find it in Gavia immer or the Loon 

 of the existing avifauna, the restoration of the infraorbital bar, as 

 shown in my figure, from the maxillary(iw^r) to the quadrate(^w) 

 must then be entirely correct. Marsh figures the quadrato- jugal 

 portions in the"Odontornithes"(Pl.I, Fig. 1 and 5, qj). With re- 

 spect to the premaxillary (t>mx) he says that they "'are elongate, and 

 separate throughout their posterior two-thirds (PI. I, Fig. 5 ). Their 

 extremities touched the frontals. Their sides are deeply excavat- 

 ed for the anterior nares, and in front they are ankylosed, and 

 form a long pointed beak, the end of which is somewhat decurved. 

 This extremity, back to the nasal openings, has its surface fitted 

 with irregular vascular foramina, indicating, apparently, that it 

 was once covered with a horny bill, as in modern birds." (P. 8.) 



This part of his description is probably quite accurate; and 

 as far as it applies to a ventral view of the superior mandible, 

 I have adhered to it in my restoration, as shown on the accompa- 

 nying Plate. It is all the more acceptable and likely to be correct, 

 in as much as he, Marsh, seems for the moment to have lost sight 

 of the ostrich or ratite skull he forever had in mind, while 

 describing the skeleton of this great, extinct, Cretaceous diver or 

 loon. As he makes no mention whatever of the maxillo-palatines 



