178 ODONTOKNITHES. 



The restoration of IcMhyomis victor, on Plate XXXIV, is also of 

 natural size, and is based on more complete material, including portions 

 of several skeletons. The other species of the genus IcMhyomis did not 

 differ widely from these in size, and this is true also of the known specimens 

 of Apatornis. 



In considering the skeleton of IcMhyomis, the anatomist is at once 

 confronted with a strange combination of characters. The wing-bones are 

 conclusive proof that IcMhyomis was a highly specialized bird, with great 

 powers of flight. The individual bones correspond closely with those of 

 birds living to-day. The legs and feet, also, are much like those of some 

 modern birds. With these portions alone before him, the comparative 

 anatomist would unhesitatingly refer the remains to the class of Birds, and 

 would naturally conclude that they belonged to the modern type. If, 

 however, the skull should then be found with the wings and feet, very 

 strong evidence would be required to convince him that they were parts of 

 one and the same bird. The jaws and teeth jjresent reptilian characters 

 wholly unknown in modem birds, while the base of the skull and the small 

 brain point strongly in the same direction. The biconcave vertebrse lead 

 IcMhyomis still farther away from all known birds, recent and extinct, and, 

 if found alone with the jaws and teeth, would force any anatomist to the 

 conclusion that he had before him the remains of a reptile. 



The skeleton of IcMhyornis, as we know it to-day, can be interpreted 

 only, in the light of modem science, by supposing that certain parts have 

 become highly specialized in the direction of recent birds, while others 

 have been derived, with but little change, from a reptilian, or even a more 

 lowly, ancestry. In the wings, the most characteristic modern feature is the 

 coossification of the metacarpal bones, a character universal among existing 

 birds. In reptiles, however, and in the only known Jurassic bird, 

 Archceopteryx, these bones are separate. The sternum of IcMhyomis is 

 very similar to that of modern carinate birds. In the feet of IcMhyomis, 

 also, the compound tarso-metatarsal is another modern feature, especially 

 characteristic of recent birds. 



