772 



CHALMER L. COOPER 



the Chester series and the Pennsylvanian 

 system. In the latter category are found 

 Bairdia, Cavellina,^ Glyptopleura, Graphia- 

 dactyllis, Healdia, and Paraparchites. 



After a marked decrease in the number of 

 species present in the Lower and Middle 

 Mississippian, an increase is again noted in 

 the Chester series. However, a few of the 



Pennsylvanian 



represented. The Chester is characterized by 

 a very great increase in the number of spe- 

 cies of Bairdia, Cavellina, Glyptopleura, 

 Healdia, and Paraparchites. Genera restrict- 

 ed to the series are Bairdiolites, Chesterella, 

 Deloia, Geffenina, Geffenites, Glyptopleur- 

 oides, Lochriella, Neokloedenella, Paracavel- 

 lina, Perprimitia, and Tetratylus. 



SEC. I,T9N..R.3E. 



SHELBY COUNTY III. 

 (SECTION BY NEWTON) 



SEC.I8.TI2N..R.9W. 



MACOUPIN COUNTY ILL. 

 (SECTION BY WANLESS) 



Permian 



NEAR WOOD-WiRT COUNTY LINE 

 WEST VA. HWY 21 



(SECTION BY COOPER) 



VA 





>- 



I 1 \ ^ 



u 



] \ \ < 



111^ 





111^ 







W VA HWY 21 ^^=^==E± 



Fig. 6. — Graphic sections of the Newton and Gimlet cyclothems of Illinois and a part 

 of the Permian section of West Virginia showing ostracode horizons. 



-JQ 



holdover genera from earHer periods con- 

 tinue their decline, namely, Beyrichia, En- 

 tomis, and Primitia. Amphissites, Bythocy- 

 pris, Ectodemites, Kirkbya, and Paraparch- 

 ites continue into the Pennsylvanian with 

 little or no change in the number of species 



® If the Paleozoic cytherellas are equivalent 

 to Cavellina, the latter originated long before 

 the Kinderhook, in the Middle Ordovician. 



Pennsylvanian. — The most common os- 

 tracodes of this period came over from the 

 Mississippian, and many genera, whose 

 roots were started in the Chester series or 

 earlier, reached culmination in the Middle or 

 Upper Pennsylvanian. In this group we find 

 Bairdia, Healdia, Hollinella, Kirkbya, 

 Knightina, Seminolites, and Waylandella. 

 The restricted genera, each represented by 



