300 STUART WELLER 



the Okaw limestone, the characteristics of the formation remain 

 much the same, although the local details are different. As in the 

 southern counties there is a succession of limestone and shale 

 members, but there is a larger content of limestone in the more 

 western region. The limestone beds themselves are crystalline in 

 texture, like those in the south, they vary in color from essentially 

 white to dark gray, the lighter colors on the whole being more 

 dominant in Monroe and Randolph counties, and the oolitic beds 

 being much more conspicuous. The shale beds are similar in the 

 two regions. 



The establishment of the continuity and equivalence of the 

 Golconda and the lower portion of the Okaw is based not alone 

 upon their occupying an equivalent position in the section, but 

 upon the paleontological characters as well. One of the notable 

 horizon markers of this lowest limestone formation of the Middle 

 Chester is the little brachiopod Camarophoria explanata. This 

 species is unknown in the Lower Chester faunas, but is a common 

 member of all the Middle Chester faunas, and is present, abun- 

 dantly in places, in some of the Upper Chester formations. The 

 horizon where it is first introduced in the section can be considered 

 as being well toward the base of the Golconda limestone. In the 

 southeastern counties of the state one of the most reliable guide 

 fossils for the lower Golconda is the Crinoid Pterotocrinus capitalis, 

 which is commonly represented by the "wing-plates" alone. This 

 species has not been recognized in Randolph or the adjoining 

 counties, but in this region the near basal beds of the lower Okaw 

 are characterized by the presence of a peculiar and very unusual 

 fauna, for the Chester series at least, composed very largely of 

 small pelecypods and gastropods, including many Bellerophontids, 

 Many of the species of this fauna are undescribed, and some of 

 them are peculiar and extraordinary. In southern Johnson County, 

 at one locality, a fauna has been collected from near the base of the 

 Golconda, in which most of these peculiar basal Okaw species are- 

 present, and associated with them are many examples of the char- 

 acteristic Pterotocrinus capitalis. This mingling of forms, so pecu- 

 liar in character, is assumed to be sufficient evidence to establish 

 the equivalent of the Golconda with the lower Okaw, and the 



