a 
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or Toothed Birds of North America. 271 
region were the toothless Pterodactyles. Ichthyornis doubtless 
competed with these huge dragons for the fishes in the tropical 
d 7 
an examination of the skull in either form, the remainder of 
the skeleton being unknown, might well lead the student as 
far from the truth in the other direction. So untrustworthy, 
in the light of modern science, has Cuvier’s law of correlation 
‘Proved to be. : 
he conclusions drawn by Professor Marsh from his study 
‘of all the known remains of Odontornithes are as follows: 
® Having now described the more important characters in 
» ‘the structure, so far as known, of the two groups of Cretaceous 
pected, 
Broove, a low, generalized character; with, however, the 
Strongly differentiated saddle-shaped vertebrae. Ichthyornis, on 
the other hand, had the primitive biconcave vertebra, and yet 
Am. Jour, es gee Vou. XXI, No. 124.—AprIL, 1881. 
