Geological Problems in Muscatine County. ii 



two sandstones do not belong to the same period, nor do they 

 even belong to the same age. The writer has handled more 

 than a thousand specimens of S^irifera capax, the specimens 

 occuring in the form of casts in the supposed Kinderhook 

 sandstone. Impressions of the external surface of the shell 

 are often very perfectly preserved, revealing every detail of 

 surface marking. From the study of such an arra}- of 

 material showing every phase and character of the species 

 there can be but one conclusion, and that is that Spirifera 

 capa.x is simply the cast of Spirifcra parryana^ Hall, a 

 species more or less common in the limestones at Buffalo — 

 limestones that Hall and Owen and Shumard, with the full 

 concurrence of all ""eolosfists who have examined the reo-ion, 

 referred to the horizon of the Hamilton Group of New York. 

 Spirifera capax is therefore a synonym of Spirifera par- 

 ryana. i 



Associated with the casts of Spirifera pan-yaiia, (6". capax), 

 in the sandstones about Pine Creek, occur the casts of such 

 typical Devonian species as Atrypa reticular is, Lin ; Spirifera 

 aspera. Hall; Strophodonta demissa, Conrad; Orthis impressa 

 or Orthis iowensis. Hall; and many other well known brachio- 

 pods. There is not a single Kinderhook species in the entire 

 beds so far as observed, nor is there a species that could by 

 any stretch or reasonable allowance be regarded as a repre- 

 sentative of any of the Carboniferous or Sub-carboniferous 

 groups. On the contrar}^ all the species are identical with 

 species occuring in the Hamilton limestones at Buffalo, Pine 

 Creek Mills, Hanson's Quarry, Atalissa and all other points 

 where limestone containing Spirifera parryana is exposed. 



The yellow sandstones above the mouth of Pine Creek 

 therefore are of the same age as the limestones near Buffalo. 

 They are not even Chemung unless the Hmestones are also 



I The two species are described and illustrated in the same publication, 

 Hall's Geolog}- of Iowa, Vol. I, part 2. S. parryana however is entitled to pre- 

 cedence since it is characterized on page 509 and Plate IV, while the description 

 and figures of 5. capax are not given until we reach page 520 and Plate VII. 



