CHAPTER XVI. 



THE RESTORATION OF ICHTHYOSIS. 

 (Plates XXVI and XXXIV.) 



The preceding description of the remains of IcMhyornis, in connection 

 "with the illustrations given in Plates XXI to XXXIV, will make known 

 most of the more important characters which separate these remarkable 

 Mesozoic birds from all others, recent or extinct. The material on which 

 the present restoration of two species of this genus are made consists of 

 portions of more than seventy different individuals. None of these various 

 skeletons were as complete, when found, as were several of Sesperornis, 

 from the same formation. This was no doubt mainly due to the smaller 

 size, and more fragile .character, of the individual bones of IcMhyornis, 

 The restoration of Apatornis, evidently a near ally of IcMhyornis, has not 

 been attempted, as the specimens at present available for this purpose are 

 not sufficiently numerous or complete. 



In the restoration of IcMhyornis dispar, as given on Plate XXVI, only 

 the remains of the type specimen are figured, as it was deemed 

 important to show the exact material on which the genus was based. 

 These portions are shaded in the restoration, and are of the natural size. 

 The bones represented in outline are taken in part from other specimens of 

 the same species, but mostly from the skeleton of the Royal Tern {Sterna 

 regia, Gambel), which, after a careful comparison, seemed well adapted for 

 completing, approximately, the restoration here presented. The jDosition 

 chosen is one which seemed on the whole to accord best with the remains 

 at present known. 



