PROBLEM I 389 



pear in Lower Ludlow, 11 and 1 doubtful in Aymestry, and 4 in Upper 

 Ludlow. 



Thus by the statistical method the Edmunds fauna is correlated with 

 the general Wenlock limestone and shale of Great Britain, because in 

 these beds the number of identical species is found to be greatest. 



Using the more refined method and comparing the Brachiopods alone 

 with the Brachiopods of the Shropshire section of England, the same 

 result is reached. The largest number of species of Brachiopods of the 

 Edmunds fauna are found in the Wenlock limestone and immediately 

 underlying shale, and running below and above that horizon the number 

 of identical species regularly decreases until they cease to appear. 



As has been shown in the first part of this paper, taking the fauna of 

 Eochester shale of New York and comparing it with the same transat- 

 lantic faunas, the correlation is the same — the Wenlock limestone and 

 immediately underlying shale — the diagnostic brachiopods in that case 

 being represented in great number in the limestone and shale. Never- 

 theless, the Edmunds fauna and the Niagara fauna of New York as rep- 

 resented by the Eochester shale do not agree. The Edmunds and Eoch- 

 ester faunas contain 6 identical Brachiopods in common ; 3 of the trans- 

 atlantic species in the Eochester shale have not been seen in the Edmunds 

 formation. In the Edmunds fauna 6 identical species of the transatlan- 

 tic Wenlock fauna have not been recorded from the Eochester shale. 

 These peculiarly Edmunds species are regarded as of particular signifi- 

 cance in determining the true relations of the Edmunds to other forma- 

 tions. 



PROBLEM J 



Definition of the problem. — The first of the problems I will define as 

 follows : 



Given two faunas separated by considerable distance from each other 

 and by this statistical method shown to be correlated, what inference can 

 be drawn as to the time-relations of the formations carrying the faunas ? 



Are they contemporaneous? and what are the grounds for deducing 

 from fossils in the rocks inferences regarding the time-relations of the 

 geological events represented by the rock formations and all the other 

 problems connected with paleogeography ? 



Huxley warned us against interpreting likeness of fossils or sediments 

 into contemporaneity. Since that statement was made much progress 

 has been made in biology as well as geology, and now it may be profitable 

 for us to turn our attention away from the fascinating ai tract ion of the 

 scientific details of our science to consider some of the fundamental />rin- 



