48 
period since the foot-tracks were discovered on Con- 
necticut River. Although his labors should be modi- 
fied by succeeding observers, Science must be ever 
grateful to him for laying the foundation, and doing 
so much for the completion, of a work so great, novel, 
and interesting. 
This inquiry seems to us to promise a rich variety ; 
and we hope that President Hitchcock and other 
observers will continue to explore and cultivate it 
with undiminished zeal. 
