STRATIGRAPHIC TAXONOMY 661 



ing further study, it may be said that the Fort Cassin fauna seems to 

 be represented in the Axeman limestone and in the upper part of the 

 Nittany dolomite by Syntrophia lateralis, Raphistoma compressum, 

 Trochonema exile, Maclurea affinis, Bathyurus caudatus, and Ribeiiia 

 compressa. 



The Canadian deposits in Oklalioma — Extent and boundaries. — Eopale- 

 ozoic deposits, beginning with the upper Cambrian Eeagan sandstone, 

 are developed in great force in the Arbuckle uplift in south central Okla- 

 homa. In part, these extend westward about the pre-Cambrian rocks in 

 the Wichita Mountains and southward into central Texas, where they are 

 again at the surface in Llano and adjoining counties. 



Published knowledge of the section in the Arbuckle Mountains we 

 owe chiefly to Taii^^, who in the course of his official work for the U. S. 

 Geological Survey, mapped part of the area of this uplift in detail. My 

 own knowledge of the stratigraphy and paleontology of the region was 

 acquired in a rather thorough reconnaissance with Mr. Taff of the three 

 uplifts, the Arbuckle, the Wichita, and central Texas. Parts of three 

 seasons, 1901, 1902, and 1908, were devoted to these investigations. 



The subdivisions of the Eopaleozoic section in the Arbuckle uplift, as 

 determined and published by Taff, are based entirely on lithologic char- 

 acters; and these were not by any means all taken into account. In 

 consequence, the boundaries of the formational units were sometimes 

 drawn very differently from where they would have been placed had 

 faunal and diastrophic evidence been allowed to dominate the choice. 

 This criticism applies especially to the great series of calcareous sedi- 

 ments comprised in the Arbuckle limestone, which, as originally de- 

 scribed and mapped by Taff, had a total thickness of quite 6,000 feet. 

 However, prior to the publication of the Tishomingo Folio certain thin 

 limestones at the base, then determined as middle Cambrian, but now 

 classed as upper Cambrian, were transferred to the underlying Eeagan 

 formation. In the present work the name Honey Creek member is 

 applied to this transferred member. 



Subdivisions of the Arbuckle limestone. — Unfortunately, in 1901 and 

 1902 my acquaintance with the great masses of unevenly distributed 

 deposits that belong between the top of the true Cambrian and the base 

 of the Saint Peter, and which are here divided into two independent 

 systems — the Ozarkian and the Canadian — was yet greatly inferior to 

 what it has since grown to be. The great Arbuckle limestone, like the 

 Knox dolomite of the Appalachian Valley, seemed an indivisible mass 



"••J. A. Taff: Tishomin«o Kolio. fJeol. Atlas V. S. Geol. Survey. 1908. 



