No. 6. — The Brachiopoda of the Maquoketa of Iowa. 



By John II. BRADLEY, Jr. 



InTBODUCTION. 



Tin. publication of a Large Dumber of new and curious trilobites 

 from the Maquoketa of ( Vermont and nearby localities in northeastern 



Iowa by Slocum lias caused renewed attention to be given to a region 

 which lias for many years been known for its fossils. In 1017, in 

 company with Prof. I*. E. Raymond, I spent a week at Clermont, 

 where, with the efficient guidance and assistance of Mr. A. II. Becker, 

 a collection of representative fossils was secured. The present paper 

 is primarily a description of the brachiopods, and though there are 

 fewer novelties among the brachiopods than were found among the 

 trilobites from the same locality, it is nevertheless true that, including 

 the eight new species, nineteen out of twenty-seven species are known 

 only from the Maquoketa. hingula bcltraini, Plcctorthis (Austinella) 

 kankahensis, P. (A.) whitfieldi, Dalmanella macrior, D. corputcnta, 

 Dinorthis proavita, Leptaena unicostata, Strophomcna acuta, S. wis- 

 consinensis, S. planodorsata, and Parastrophia divergent are, w^ith few 

 exceptions, restricted to the highest Ordovician of Iowa, Minnesota, 

 and Wisconsin, and none of them has been found in Ohio or Indiana. 

 Five of the remaining eight species, Hebertella insculpta, Placsiomys 

 svbquadrata, Strophomena neglecta, S. nutans, and Rhynchotrema capax 

 are characteristic fossils of the typical Richmond, while three, Crania 

 laelia, Hebertella sinuata, and Plectambonites rugosus, are found in 

 both the Cincinnatian and Richmond. 



The Trentonian aspect of the fauna is expressed in some of the 

 Strophomenae, in the small Plectambonites and Zygospira, and in the 

 presence of Parastrophia. The dominant facies is, however, Rich- 

 mondian, though none of the typical fossils of the late Richmond is 

 present. 



Maquoketa Shale. 



Position and Distribution: — Few formations have been more 

 written about or more misunderstood than the Maquoketa shale. 

 Hall, the first to recognize it, called it the " Hudson River formation," 

 a term which is now bereft of meaning. It was first formally labeled 

 "Maquoketa shale" in 1870 by White, who supposed it to represent 



