18 THE AMERICAN MIDLAND NATURALIST 
Stromatopora reefs just below the iron bridge, at Treats quarry, 
Kelleys Quarry, at Charles City, Iowa, in the upper part of the 
Middle Devonian. ‘ 
Now in the author’s collection. 
Atrypa subhannibalensis N. Sp. 
Plate VIII. Figs. 15-16. 
Shell of medium size, wider than high, both valves convex; 
dorsal valve extremely convex with greatest convexity about the 
centre, prominent elevation in the centre correspondimg to a mesial 
fold and especially strong at the front margin of the valve; cardinal 
extremities rounded; ventral valve much less convex than the 
dorsal with a prominent mesial sinus especially well developed 
on the front margin of the valve; hinge line much shorter than the 
greatest width of the valves, area closed, beak sharply incurved, 
perforation of ventral beak not well made out. Surface marked 
by many strong and prominent imbricating lines of growth, and 
and at times these lines are marked by broad and slight elevations. 
In general appearance this form might be considered as occupying 
a position between the genus Atrypa and the genus Athyris, al- 
though I am convinced it really is referable to the former. In- 
general appearance and expression also it has a quite strong resem 
blance to Athyris Hannibalensis of the Carboniferous above. 
Position and locality: Upper Hackberry Group, (equivalent of 
the ‘““Owen Sub-Stage’’ of Fenton) Devonian, Owens Grove 
(south exposure), Cerro Gordo County, Iowa. 
Now in the author’s collection. 
Atrypa aspera var. occidentalis, Hall. 
This variety of A. aspera occurs abundantly at Independence, 
Waverly, Janesville, and a few other localities, in Iowa, and is « 
typical western form. Through the kindness,of Professor E. M. 
Kindle, chief paleontologist of the Canadian Geological Survey, I 
have received identically the same variety from the upper part of 
the Manitoba formation (Devonian), Red Deer River, Manitoba, 
Canada. . ° 
This is a fact of much scientific interest. Professor Kindle is 
now at work on his great collection of Devonign fossils from the 
Northwest Territory, Canada, and his conclusions on the corelation - 
of fauna—especially as they relate to the fauna of the Canadian 
