836 



DEPARTMENT OF TEE INTERIOR 



2 GEORGE V., A. 1912 



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Myrica serrata has no precise equivalent in any of the groups with which 

 comparison has been made. The general distribution of the genus has been 

 fairly well represented in the list given by Knowlton (37), which shows that 

 out of the fifty-three species, less than half are Cretaceous, although they range 

 as far down as the Potomac formation. From this it is apparent that while 

 specific forms may be definitely associated with particular horizons, the general 

 f acies of the genus as a whole is such as to indicate an Upper Cretaceous or even 

 Tertiary contact, rather than a Lower Cretaceous. 



Populus cyclophylla, Heer, and Sassafras cretaceum, Newb. (46: p. 98), are 

 both well defined elements of the Dakota flora, and they thereby give a some- 

 what definite indication of a specific horizon, which is certainly Upper Creta- 

 ceous. Again, both Quercus flexuosa, Newb., and Q. coriacea, Newb., are known 

 so far only in the Puget Sound group of Chuckanutz, Washington (46: pp. 73, 

 74), once more giving a definitely Upper Cretaceous horizon. Similarly also, 

 Cycadites unjiga, Dn., from the Upper Cretaceous of the Peace river, compared 

 by Dawson (9 : p. 20) with C. dicksoni, Heer, from the Upper Cretaceous of 

 Greenland, confirms the deductions to be drawn from the foregoing facts in a 

 very striking manner, especially as Dawson has already shown the Peace River 

 formation to be Senonian, and thus within the limits of the Chico. Cladophlebis 

 is a very strongly pronounced Cretaceous type, which is largely found in the 

 Potomac formation, though it is also common to the Upper Cretaceous of 

 Vancouver island, from which locality Dawson has described C. Columbiana 

 (12: iv., 55), a type, however, which is quite distinct from those generally 

 associated with the Cretaceous, and which affords no direct point of comparison 

 with the present species. 



