Extinct Birds from Patagonia. 5 



with other birds, recent and fossil, may give valuable 

 indications of the probable direction in which the nearest 

 relatives of the extinct species should be sought; bnt all 

 conclusions derived from such comparisons must necessarily 

 be regarded as only provisional, and subject to revision on 

 the discovery of more perfect specimens. 



Comparison of the skull of Phororhacos with as much as is 

 known of that of Gastornis does not seem to reveal sufficient 

 resemblances to justify the inclusion of the latter in the 

 Stereornithes. The more important differences are : — 



(1) The presence of teeth in Gastornis, the former state- 

 ment that these exist in Phororhacos having been ascertained 

 to be erroneous. 



(2) The small size of the temporal fossae and the sloping 

 occipital surface of Gastornis. 



(8) The great length of the parietal region in the European 

 bird, giving the skull an aspect totally different from that of 

 Phororhacos. 



(J-) The presence of a pointed angular process in the 

 mandible of Gastornis. 



Another point which tells against the association of the 

 Gastornithidse with the Stereornithes is that, although both 

 are said to occur in the Lower Eocene, the associated mam- 

 malian fauna renders it almost certain that the so-called 

 Lower Eocene of South America is of a much later date, and 

 is probably synchronous with some part of the Miocene 

 elsewhere. With regard to Dasornis all that can be said is 

 that the cranium is much depressed, as in Phororhacos, but 

 the specimen upon wliicii the genus was founded is so 

 imperfect that even its avian nature has been called into 

 question. 



The skull in the Ratitge differs from that of Phororhacos 

 mainly in the presence of a single head to the quadrate. 

 The beak, also, is much depressed, except in Casuarius and 

 Apteryx, and the nostrils impervious. The angle of the 

 mandd)le is truncated, as in the Stereornithes. 



The skulls of Hesperornis and Ichthyomis are sharply 

 separated from that of Phororhacos by the possession of 



