334 The Ohio Journal of Science [Vol. XVI, No. 8, 



a fair sized movement would be quite conspicuous. Yet even 

 a fair-sized movement probably would show little or no effect 

 upon the main sedimentation or upon the life of the sea as a 

 whole. 



Such appears to be the case with the Maysville-Richmond 

 break. We should naturally expect to find breaks about the 

 shores of the interior sea of this time, and we do get them in 

 New York, Pennsylvania, Tennessee, etc., but over the broad 

 interior, there is but scanty and obscure evidence of such a 

 break. 



It is not intended to deny the presence of such a break, but 

 this break is held to have been the result of a broad though 

 feebly developed and fleeting upwarping, not to be compared 

 either physically or faunally in its results with later movements. 



If the Arnheim be taken as the basal member of the Rich- 

 mond, then it cannot be said that there is any definite physical 

 break between the Maysville and the Richmond, at least in 

 Ohio, Indiana and Kentucky. 



The evidence as shown in overlap irregularities in sequence 

 and thickness of deposits is inconsistent and obscure at the 

 best. And the evidence is much less distinct than it is in the 

 case of the breaks at the top of the Arnheim, at the base of the 

 Whitewater (Gyroceras baeri zone, where in Adams County 

 and elsewhere there is a veritable basal conglomerate), at the 

 base of the Saluda, within the Saluda and at the top of the 

 Saluda-Elkhorn. 



To summarize the evidence here presented, the Maysville- 

 Richmond break is found to be inconvenient and inadequate 

 physically. Regardless of the evidence of physical breaks, the 

 close relationships of the two faunas speak for itself. 



And the radical difference between the faunas of the Rich- 

 mond and the Upper Medina-Clinton indicates a greater period 

 of disturbance and a greater letting down of barriers than 

 in the case of the close of the Maysville. 



To make a few more comparisons, 58 times as many Mays- 

 ville as Richmond species pass on up; 4 times as many new 

 genera and 7 times as many new families are introduced during 

 the Upper Medina-Clinton as are introduced during the Rich- 

 mond ; nearly 5 times as many families close with the Richmond 

 as close with Maysville; 3 times as many genera failed to pass 



