1889.] Description of the Devonian Rocks of Iowa. 239 
This formation carries two faunas ; one at the base, and another 
occupying the remainder of the division. 
The fauna at the base is represented by considerable numbers of 
very minute, and finely preserved Brachiopoda, Gastropoda, Crus- 
taceans, Foraminifers and Corals, a large number of which are 
as yet' undescribed. 
Not more than one or two of the forms, occurring at the base of 
the shales, are known to occur outside this formation. 
Of the described species of this fauna, the following may be enu- 
merated. 
Athyris minutissima. C. L. Webster. 
Platystoma mirum. Webster. 
pervetum. Webster. 
Naticopsis rarus. Webster. 
Turbo strigillata. Webster. 
" incerta. Webster. 
Holopea tenuicarinata. Webster. 
Cyclonema brevilineatum. Webster. 
" subcrenulatum. Webster. 
For a more detailed description of this fauna etc., reference may 
be made to a paper on " Description of New Species of Fossils 
From the Rockford Shales of Iowa," which appeared in the No- 
vember number of this Journal for 1888. 
Of some of the described species which constitute the fauna of 
the higher horizon, and which are mostly typical of it, the follow- 
ing may be given. 
Rhynchonella subacuminata. Webster 
Paracyclas sabini. White. 
" validalinea. Webster. 
" var planosulcata. Webster. 
var elongata. Webster. 
Spirifera whitneyi 
" hungerfordii. 
strigosus. Meek, {S. orestes, H. and W). 
" substrigosus. Webster. 
norwoodii. Meek, {S. cyrtinaeformis, H. and W). 
" fimbriata. 
" macbridei. 
