or Toothed Birds of North America. 259 
very stout. In form they closely resemble the teeth of some 
Mosasauroid reptiles. 
There were fourteen functional teeth in the maxillary bone 
of Hesperornis regalis, the premaxillary being edentulous, while 
The brain of Hesperornis (figure 1) was very small and 
a 2. 
Ss 
5 
a 
Compared with the brain of Colymbus (figure 2) the brain 
esperornis presents some interesting features. It was less 
= &, 
Ss 
. gt feeble, and there were no functional wings; the only bone 
© the arm represented being the humerus, which had no artie- 
ular surface at its distal end. The sternum was broad and 
