DISTRIBUTION OF PALEOZOIC OSTRACODES 



771 



the introduction of many new genera in the 

 Devonian serves to change the faunal facies 

 almost completely. 



The Lower Devonian fauna is made up 

 largely of genera from the Haragan (Helder- 

 bergian) of Oklahoma and the Shriver chert 

 (Oriskanian) of West Virginia. Genera which 

 are restricted to or reach their culmination 

 in these formations are Acanthoscapha, Con- 

 dracypris, Kloedenia, and Thlipsurella. 



Ostracodes are almost entirely wanting in 

 the Upper Devonian of North America. The 

 complete record includes Beyrichia dragon, 

 Geneseo, New York; Entomis serratostriatus 

 and Primitia variostriata, Naples, New 

 York; and Kloedenia simplex, Kings Mill, 

 Pennsylvania. A large number of Upper De- 

 vonian species are found in the Eifel, Hartz, 

 Saurland, etc., of Europe and South Devon 

 in Great Britain. Common genera are En- 



SEC. 17. TeN,R3E. 



FULTON COUNTY, ILL. 



(SECTION BY WANLESS) 



SEC 2.TIIN,R I2E. 

 Clark County, ill. 



fSECTION BY NEWTON) 



SEC 17, T6N,R.4E. 

 FULTON COUNTY, ILL. 



(SECTION BY WANLESS) 



Fig. 5. 



-Graphic sections of the Liverpool, Bogota, and St. David cyclothems from the 

 Pennsylvanian of Illinois, showing location of ostracode-bearing beds. 



The Middle Devonian is best known be- 

 cause of the very excellently preserved ma- 

 terial of the Hamilton at Arkona, Ontario, 

 and from species described from the Silica 

 shale of northern Ohio, and the Traverse 

 beds of Michigan. Representative genera are 

 Barychilina, Bufina, Burlella, Euglyphella, 

 Favulella, Hamiltonella, Hollina, Pondero- 

 dictya, and Quasillites. Many "firsts" of gen- 

 era of later importance are recorded, namely 

 Amphissites (?),^ Bairdia (?), Cavellina, 

 Hollinella, and Kirkhya (?). 



5 The queries indicate that the genera may 

 have an earlier existence in species of doubtful 

 affinity. 



tomis (Richterina) , Haploprimitia, Nehden- 

 tomis, and Polycope. 



Bollia, Ctenobolbina, Halliella, Haplopri- 

 mitia, Isochilina, Kloedenia, Leperditia, Oc- 

 tonaria, Primitia (?), and Ulrichia (?) be- 

 come extinct during this period. 



Mississippian. — Several Devonian genera 

 continue with little change into the Lower 

 Mississippian, chiefly Bairdia, Hollinella, 

 and Tetrasacculus. On the whole the Lower 

 and Middle Mississippian have furnished 

 little in the way of diagnostic ostracodes. 

 Most of the common genera have either 

 come over from the Devonian or are the 

 early representatives of genera common in 



