Some Geological Problems — Calvin. 29 
During the past ten years the writer has made repeated excur- 
sions to the region near the mouth of Pine creek, atracted first by 
unusual facilities offered for collecting beautifully preserved 
casts of the so-called Spirifera capax, and afterward by the de- 
sire to study anew the stratigraphical phenomena of the region. 
A very casual study of the facts now available in determining 
the geological problems of the region in question, is suflScient 
to demonstrate that the spirifer-bearing sandstone at Pine creek 
is not the stratigraphical equivalent of the Kinderhook sand- 
stone at Burlington. The 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 Spiri- 
fera capax^ the specimens occurring 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 
array of material showing every phase and character of the 
species there can be but one conclusion, and that is that Spiri- 
fera capax is simply the cast of Spirifera iMrryana 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 geologists who have examined the region, 
referred to the horizon of the Hamilton group of New York. 
Spirifera capax is therefore a synonym of Spirifera parryana* 
Associated with the casts of Spirifera parryana {S. capax)^ 
in the sandstones about Pine creek, occur the casts of such 
typical Devonian species as Atrypa reticularis Lin; Spirifera 
■aspera Hall; Strophodonta demissa Conrad; Orthis impressa or 
Orthis iowensis Hall; and many other well known brachiopods. 
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 reaso'iable allowance be regarded as a representative 
of any of the Carboniferous or Sub-carboniferous groups. On 
the contrary all the species are identical with species occurring 
in the Hamilton limestones at Buffalo, Pine creek Mills, Han- 
*The two species are described and illustrated in the same publication, 
Hall's Geology of Iowa, vol. i, part 3. 8. parryana however is entitled to 
precedence since it is characterized on page 509 and I'late IV, while the 
description and figures of .S'. cafax are not given until we reach page 520 
and Plate VII. 
