PROBLEM II 393 



usage in the application of the specific names to morphologic characters 

 of the fossils described. 



The effect is to make a list of identical species to be composed of a 

 group of morphologic units of very diverse scientific value. 



We would not expect to get accurate results regarding geographical 

 boundaries by promiscuously adding together yards, feet, and meters, 

 and can we expect to reach correct conclusions regarding correlations by 

 comparing statistics of such diverse meaning. In the past fifty years a 

 great amount of attention has been given to establishing uniformity of 

 classification and nomenclature of geologic formations. I raise the ques- 

 tion whether the time is not ripe for us paleontologists to give thought 

 and study and conference to solving the difficult problems facing any one 

 who attempts seriously to correlate formations by means of their fossil 

 contents. 



PROBLEM II 



General discussion of the problem. — The second problem to which I 

 wish to call attention concerns the use of fossils in making inferences as 

 to tne physical conditions of the area in which they lived and the geo- 

 logical events signified by change in fossil faunas. 



In what I have to say you must bear in mind that my scientific study 

 of fossils has been limited to Paleozoic faunas, the great part of the spe- 

 cies of which are now marine and extinct. Those who are more familiar 

 with higher formations, in which living genera and species come into 

 evidence, and students of land fossils of higher biological rank may con- 

 tribute valuable suggestions in the solution of these problems which I 

 can not speak of from personal knowledge. 



In the study of Paleozoic faunas we have reached certain conclusions 

 regarding the original nature of the environmental condition under 

 which the fossils lived by noting the physical character of the sediments 

 and in a general way by observing the adjustments now existing of the 

 classes of organisms represented in these ancient faunas. Thus when we 

 discover a fauna limited to Lingulas, a few frail mollusks, and fragments 

 of fish remains and driftwood we interpret it as evidence of shallow water 

 marine environment. 



When we discover corals in abundance, Brachiopods and Cephalopods 

 dominant in the composition of the fauna, and the sediments more or 

 less calcareous, we interpret it into deeper marine conditions, open at 

 least to the ocean conditions as far as determination of the kind of the 

 life is concerned. 



From the coarseness and fineness of the detrital materials making up 

 XXVII— Bull. Gbol. Soc. Am., Vol. 24, 1012 



