186 ODOXTOKNITHES. 



It would be highly desirable to carefully compare both Ichthyomis 

 and Hesperomis with Archceopteryx, the still older Mesozoic bird. This 

 unfortunately cannot be done at present, as the two skeletons of 

 Archceopteryx, now known, have not yet been folly described, nor even 

 prepared for examination by removal of the matrix. That Archceopteryx 

 belongs to the Odontomithes, the writer fully satisfied himself by a personal 

 examination of the well known specimen in the British Museum. This 

 examination was made in 1878, several years after the writer had become 

 familiar with the American forms of toothed birds. The teeth seen on the 

 same slab with this specimen of Archceopteryx, and referred to it by 

 Evans, although imperfectly preserved, agree so closely with the teeth of 

 Hesperomis, that the writer identified them at once as those of Birds, and not 

 of Fishes. It has since been announced that the specimen of Archceopteryx, 

 more recently found in Grermany, also possessed teeth, although only two 

 of small size were detected. The separate metacarpal bones, and especially 

 the elongated tail, of Archceopteryx, moreover, remove it widely from the 

 known American genera of Odontomithes. It will probably be found, 

 however, that Archceopteryx possessed biconcave vertebrae, somewhat like 

 those of Ichthyomis. 



The other Mesozoic birds now known from the deposits of this country, 

 and the few discovered in Europe, may, some or all of them, have had 

 teeth, but their remains are too fragmentary to determine this point, or 

 even their near affinities. 



It is an interesting fact that the Cretaceous birds at present known, 

 some twenty species or more, were all apparently aquatic forms, 

 which are of course most likely to be preserved in marine deposits, 

 while the Jurassic Archceopterxjx, the only one from that formation, was a 

 true land bird. 



The Birds found in more recent formations all belong apparently to 

 modern types, and hence present few points for profitable comparison 

 with the Odontomithes. The existing birds with reptilian characters are 

 nearly all confined to the Ratitce, or Ostrich tribe. These are evidently the 

 remnants of a very numerous group, once widely extended over different 



