WAVERLY GROUP. 515 



At the very summit of the Waverly is a band of variable thickness 

 which carries a rich though poorly preserved fauna. It is exposed' 

 at various places near Rushville and on the summits of the hills 

 west of Portsmouth, and especially immediately below the carboniferous 

 conglomerate near Loudonville. The rock is a crumbling red sandstone 

 with numerous casts of fossil which, on the whole, resemble those of the 

 Keokuk of Illinois more than any other known assemblage. Phillipsia 

 meramxcensis, P. serraticaudata, Cythere ohioensis, Cytherella union- 

 iformis, Chonetes illinoisensis, Productus burlingtonesis \ Pmductus rush- 

 villensis, Productus nodocostalus, and a few bryozoa are common species; 

 a small Cypricardinia like C. scitula is also associated with Spirifer ps. u- 

 dolineatus at these localities. In the tabulated list of Waverly fossils, 

 given by Mr. Cooper in the fourth volume of the Bulletins of Denisou 

 University, there are a number of species of bryozoa, crinoids, and a 

 few other forms referred to this horizon upon the supposition that the 

 upper fossiliferous horizon at Cuyahoga Falls was equivalent to the 

 Keokuk, as suggested by Mr. Ulrich. This position, we have already 

 seen, is now untenable. It is very desirable that the few localities 

 where this horizon is undisturbed by erosion should be carefully 

 studied. At Sciotoville extensive erosion of the surface of the 

 Waverly preceded the deposition of the fire-clay, which here forms the 

 base of the coal measures. The Keokuk is entirely removed^ and the 

 combined thickness of the Waverly correspondingly reduced. 



In conclusion, it may be remarked that the study of the series of de- 

 posits long known as the Waverly group of Ohio affords suggestive data 

 toward the solution of many of the perplexing problems connected with 

 the transition in America from Devonian to Carboniferous faunas. The 

 unif rmity of physical conditions permitting the deposition of materials 

 lithologically so constant for a long period enable us to study the almost 

 unbroken transition and slow evolution of the faunas of distant horizons. 

 Upon this background of uniformity the striking limitations imposed by 

 many stations upon the life supported in them, become allthe more con- 

 spicuous. The fact that the slow migrations of aquatic forms in the di- 

 rection of the slow oscillatory movements of the crust bring unrelated 

 stations into juxtaposition, has been well illustrated in the course of 

 these studies. It is thus, for example, that the seemingly isolated oc- 

 currence of a collection of Michigan "Marshall group" species beneath 

 conglomerate I is to be explained. Among the most interesting paleon- 

 tological results is the evidence that the Carboniferous trilobites evolved 

 gradually from Devonian genera during the period represented by the 

 Waverly, and while the conditions in New York were unfavorable to the 

 existence of these animals. No portion of the series is without trilobites 

 in Ohio. In a single word, we have represented, in the Waverly series a 

 large segment of what has long seemed a missing interval in American 

 geological history. 



