EXPLANATION OF PLATE 55. 



Unilateral Knives. 

 Fig. 1. Brown Jasi'er. 



(Cat. No. 31583, U.S.N.M. (Locality uuknowii.) Dr. T. H. Bean.) 

 Fig. 2. Pale-gray Flint. 



(Uat. No. 32753. U.S.N.M. Kichmoud, Jefferson County, Ohio. Samuel Houston.) 



Fig. 3. Pink Flint. 



(Cat. No. 171459, U.S.N.M. Burke County, Georgia. Dr. R. Steiner.) 



Fig. 4. Gray Flint. 



(Cat. No. 62104, U.S.N.M. Mason County, We.st Virginia. R.W.Mercer.) 



Fig 5, Flint. 



(Cat. No. 30179, U.S.N.M. (cast). Illinois. Dr. -J. F. Snyder.) 



Fig. 6. Gray Flint. 



(Cat. No. 59221, U.S.N.M. Tennessee. C. L. Stratton.) 



Fig. 7. White Flint. 



(Cat. No. 196505, U.S.N.M. Louisiana. I'hillips collection.) 



Fig. .s. White Flint. 



(Cat. No. 4935, U.S.N.M. Illinois.) 



