)UN 16 1909 



THE FAUNA OF THE KESIDUARY AUBURN 

 CHERT OF LINCOLN COUNTY, MISSOURI* 



E, B. Branson, 



The silicified fossils which represent the fauna de- 

 scribed in this paper occur in an exceedingly fine, porous, 

 siliceous matrix, almost chalk-like in appearance. The 

 masses of this siliceous material, which is evidently a 

 decomposed chert, occur imbedded in a red residuary clay 

 exposed in the gutters by the roadside, a short distance 

 east of Auburn, Lincoln County, Missouri. In 1896, Dr. 

 Stuart Weller collected some of these masses and the fos- 

 sils have been removed from them in the museum. 



Seventy species are here recognized in the fauna be- 

 sides several species of crinoids (represented by the col- 

 umns only), bryozoans and pelycopods too fragmentary to 

 be referred to their proper genera. Of the species recog- 

 nized, forty-three have been described, eleven are new and 

 are here described for the first time, and sixteen are un- 

 identified. Thirty-three of the old species are recorded in 

 the Geological Survey of Minnesota, m., as occurring 

 in the Minnesota region, and of these eighteen occur in 

 the Stones River group, sixteen in the Black River, four- 

 teen in the Trenton, three in the Utica, and four in the 

 Richmond. 



The presence of such species as DahiKOiella suhaequata, 

 Orthis tricenaria, Zygospira nicolleti, and Lophospira 

 peraugulata in large numbers fixes the age of this forma- 

 tion as low in the Mohawkian. Dalmanella testudinaria 

 and Ctenodonta medialis, not hitherto recorded from be- 

 low the Black River, are well represented and Hindia 

 parva, Lichenaria typa, Carinaropsis pJialeria, Carina- 

 ropsis acuta, Lopliospira oiveni, and St rospho stylus tex- 

 tilus, not recorded elsewhere from below the Black River, 



* Presented by title to The Academy of Science of St. Louis, March 18, 

 1907. 



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