240 bulletin: museum of comparative zoology. 



Field and the writer, a zone of dark limestone, containing such typical 

 Leray (Black River) species as Columnaria haUi and Maclurites logani, 

 is followed by more argillaceous limestone containing Echinosphaerites 

 and a large number of other fossils. Christiania has not yet been 

 found in the Bellefonte section, but this section does definitely show 

 that the Echinosphaerites zone is there younger than the Leray — 

 Black River of New York. As shown by Mr. Field, there is essential 

 agreement between the section at Bellefonte and that at Chambersburg 

 and Strasburg, so that all three of these occurrences of Echinosphae- 

 rites may be dated definitely as post-Leray. 



According to Ulrich (119), the Kimmswick limestone at Thebes, 

 Illinois, and Cape Girardeau, Missouri, has at the top a bed of crystal- 

 line limestone, from five to thirty feet in thickness, which contains 

 Echinosphaerites and Comarocystites, among other fossils. The 

 Kimmswick at this locality can not be definitely placed in the section, 

 except that it is post-Lowville. In the Nashville dome in Tennessee 

 a formation correlated by Ulrich with the Kimmswick and containing 

 Echinosphaerites has been found at Aspen Hill, where it is forty feet 

 thick, and followed by the Hermitage, the Bigby, and the Catheys 

 formations. The contact with the underlying formation is not shown 

 but Ulrich states that there is no doubt that it rests upon the 

 Carters, which is the equivalent of the Leray or Lowville of New York 

 so that it may safely be stated that here again the Echinosphaerites 

 bed is post-Leray. At this locality we have the Echinosphaerites 

 wdthout Christiania, and the zone apparently corresponds to the lower 

 zone at Chambersburg, Strasburg, and Bellefonte. In this case the 

 formation containing the Echinosphaerites is limited above by the 

 Hermitage formation, a formation which can not be correlated with 

 any New York formation, but which corresponds to the Logana of 

 Kentucky and is also found at Bellefonte above the zone of Echino- 

 sphaerites. The Hermitage is followed above by the Bigby limestone, 

 which contains a fauna corresponding to that of the Prasopora zone, 

 or Middle Trenton of New York and Ontario. The Kimmswick lime- 

 stone, and the corresponding Echinosphaerites zone in Pennsylvania 

 and north-central Virginia, may therefore be correlated with some 

 confidence with the lower part of the Trenton of New York. 



The other occurrence of Echinosphaerites in the Appalachian region 

 is in the Ottosee formation of southwestern Virginia and eastern 

 Tennessee. Dr. Ulrich believes that the Ottosee is older than the 

 Lowville, and, if this can be shown to be correct, then this zone is 

 older than the two already discussed. A good section showing the 



