Xo. 6. — The Brachiopoda of the Maquoketa of loxca. 

 By John H. Bradley, Jr. 



ixtroduction. 



The publication of a large number of new and curious trilobites 

 from the ^Maquoketa of Clermont and nearby localities in northeastern 

 Iowa bv Slocum has caused renewed attention to be given to a resrion 

 which has for many years been known for its fossils. In 1917, in 

 company with Prof. P. E. Ra\Tnond, I spent a week at Clermont, 

 where, with the efficient guidance and assistance of Mr. A. H. 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 IMaquoketa. Lingula beUrami, PlectortMs (Austinella) 

 ka7ikake72sw, P. (A.) ichiffiekU, DalmaneUa macrior, D. corpulenta, 

 Dinorthis proavita, Leptaena unicosiata, Sirophomena acuta, S. icis- 

 consinensis, S. pJanodorsata, and Parastrophia divergcns are, with few 

 exceptions, restricted to the highest Ordo\-ician of Iowa, ^Minnesota, 

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

 Five of the remaining eight species, HeberteUa insculpia, Plaesiomys 

 suhquadrata, Strophomena neglecfa, S. juitans, and Rhynchotrema capax 

 are characteristic fossils of the t\-pical Richmond, while three, Crania 

 laclia, HeberteUa' sinuata, and Plectambcmites 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 t}-pical fossils of the late Richmond is 

 present. 



]Maquoketa Shale. 



Position and Distribution: — Few formations have been more 

 wTitten 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 

 "^laquoketa shale" in 1S70 by "NMiite, who supposed it to represent 



