Some Geological Problems — Calvin. 
33 
The Devonian sandstone, as developed at and near Mont¬ 
pelier, seems not to have a very wide geographical distribution. 
The conditions favoring its deposition were evidently local. 
In the particular locality affected by them, these conditions, 
whatever they may have been, operated disastrously on most of 
the Devonian fauna. During a part of the time, however, 
Spirifera parryana found the conditions unusually favorable. 
The great number of casts of this species occurring in the 
spirifer-bearing layer would indicate that the sea-bottom was 
fairly crowded for a time with large, healthy, vigorous individ¬ 
uals; and that the species occupied the region to the almost 
total exclusion of everything else. Spirifera aspera , the con¬ 
stant associate of S. parryana in the underlying limestones is 
almost entirely absent, only two or three S. aspera being seen 
among many hundred S. parryana. Even Atrypa reticularis , 
that most ubiquitous of all Devonian brachiopods, apparently 
capable of living anywhere and under any circumstances, was 
represented by a comparatively few widely scattered individuals. 
The Orthis ioivensis attained a larger size than usual, but the 
number of individuals was small. Athyris vittata which is 
one of the most abundant shells in the subjacent limestones, is 
unrepresented in collections from the sandstone. In the fossil- 
iferous portion of the sandstone individuals of Strophodonta 
demissa are about as numerous as in the limestone. 
It is only in one layer, and that not very thick, that Spiri¬ 
fera parryana occurs. Some of the species mentioned persis¬ 
ted after S. parryana abandoned the struggle. They range a 
foot or two above the spirifer bed, but brachiopod life soon 
ceased, and the sandstone through several feet of its thickness 
shows no traces of fossils. 
There is but a siugle fish tooth in the collections from the 
sandstone, and it is apparently identical with an undetermined 
species occuring in the Hamilton limestones at Solon and Iowa 
City. 
The most significant facts recorded in the Devonian and 
Carboniferous strata of Muscatine county have been recogniz¬ 
ed by all geologist who have personally examined the region. 
These facts are detailed with scientific minuteness in the re¬ 
ports on the geology of Iowa and Illinois. Briefly stated, we 
have evidence that at the close of the Hamilton period, after 
