NOTES ON THE OSTEOLOGY AND RELATIONSHIP OF THE 

 FOSSIL BIRDS OF THE GENERA HESPERORNIS HAR- 

 GERIA BAPTORNIS AND DIATRYMA. 



By Frederic A. Lucas, 



Acting Curator, Section of Vertebrate Fossils. 



Our knowledge of the few Cretaceous birds that have been discov- 

 ered in North America is very imperfect in spite of Professor Marsh's 

 memoir on the Odontonithes; their origin and man}^ points of their 

 structure are still unknown and their relationship uncertain. By the 

 kindness of Professor Williston, I am able to add a little to our knowl- 

 edge of the structure of ITe><per<yrniH grdcUlH and Bdj^tornis advenus^ 

 while the acquisition of a specimen of IL'sperornis regalis, by the 

 United States National Museum, enables me to add a few details con- 

 cerning that species. 



CRANIUM OF HESPERORNIS GRACILIS. ' 



The example of Ilesperornis gracilh belongs to the Universit}'' of 

 Kansas, and comprises a large portion of the skeleton, including the 

 skull. Unfortunately the neck was doubled backward, so that the 

 skull lay against the pelvis, while portions of dorsal and sternal ribs 

 had become crushed into and intimately associated with the cranium, 

 so that it was impossible to make or.t the shape of the palatal bones, 

 provided even they were present. This was particularly unfortunate, 

 as information as to the character of the palate of the toothed birds is 

 greatly to be desired. Theoretically, the arrangement of the bones of 

 the palate should be somewhat reptilian, or, if the struthious ])irds are 

 survivals, the palate of such a bird as Hesperornis should present some 

 droma^ognathous characters. But, as was pointed out by D'Arc}^ 

 Thompson, the skull of Hc'iperoniU regall^^ as described and figured 

 by Marsh, differs very considcra])ly from that of an ostrich, and the 

 present specimen emphasizes oi' adds to th(^ dili'orences already noted. 

 The presence of depressions for su})raorl)ital glands and the size of the 

 sagittal and lamlxloidal crests neitlier denotes affinities with grebes 

 and loons nor separation from struthious forms, since these characters 

 are associated with aijuatic juid predatory habits and have no morpho- 

 logical value. 



Proceedings U. S. National Museum, Vol. XXVI— No. 1320. 



545 



