IOWA ACADEMY OP SCIENCES. 
21 
found above the state quarry stone. The anomalous relations 
of this formation, the limited areas to which it is confined, the 
abrupt manner in which it appears and disappears, sometimes 
at the level of one member of the Cedar valley section and some- 
times at the level of another, all lead to the conclusion that it 
was deposited uncomformably on the Cedar valley limestone 
after the lapse of a considerable erosion interval. The same 
view is even more strongly suggested by the fact that in certain 
respects the fauna of the state quarry beds is unique. The 
deposit near Solon furnishes Pugnax pugnus Martin, Melocrinus 
calvini Wachsmuth, and a very peculiar Strom atoporoid, none 
of which are found in the other Devonian formations. Of other 
species that have a greater vertical range, as for example 
Atrypa reticularis^ there is sufficient variation to distinguish 
them from individuals of the same species found at other 
horizons. The Orthothetes, so common in the beds in section 
5 of Penn township, is associated with Pugnax, and like it is 
limited to the state quarry stage. The great mass of cemented 
crinoidal debris composing the beds in (^aham township and 
the upper ten or fifteen feet of the formation at the state quar- 
ries has no parallel in any other stage of the Iowa Devonian. 
The presence of Dipterus, which elsewhere occurs only in the 
U pper Devonian, is likewise indicative of an interval between 
this stage and the Cedar valley beds below. In this connection 
it may be noted that the affinities of Pugnax pugnus is with the 
Carboniferous rather than the Devonian. These facts, coupled 
with the evidence of unconformity, would seem to place the 
formation near the closing stage of the Upper Devonian system, 
while the faunas of the Cedar valley stage correlate it with the 
Middle Devonian. The known phenomena concerning the state 
quarry limestone and its interesting fauna evidently require for 
their interpretation a number of crustal movements and a long 
period of erosion in the Iowa Devonian heretofore unsuspected. 
