Explanation of Plate X. 



Fig. 1. The entrance to the Concannon cave is shown at the right. 

 Extending from it toward the left is an artificial embankment made of 

 material taken from the cave. In 1903 the Missouri river floods covered 

 the basal portion of this embankment. The bed of the streamlet is 

 shown in the foreground. Looking east of south. (See pp. 351—2.) 



Fig. 2. Looking west of south. The entrance to the cave, and the 

 artificial embankment show to the right. In the right foreground is a 

 portion of the talus d. (See p. 352.) 



