434 S. Calwin—Fauna at Lime Creek, Towa. 
Chonophyllum and Cystiphyllum among its corals, is © strik- 
ingly Carboniferous in aspect” (this Journal for February, p. 98) 
is an opinion that will not be shared by many paleontologists. 
Even the little Productus, Productella dissimilis Hall, that Pro- 
fessor Williams regards as so “ decidedly Carboniferous in aspect’ 
(10th line, 1st par.) is a true Devonian type; and there 1s not 
another species in the whole list that even remotely suggests 
any Carboniferous affinities. 
Spirifera fimbriata, as far as I know, occurs in eastern strata 
belonging to the Upper Helderberg and Hamilton ; not in the 
‘Chemung. Now the specimens found at Lime Creek agree 1n 
size with the Upper Helderberg rather than with the Hamilton 
forms, a fact that, so far as it has any significance, points 
toward the lower Devonian rather than in the opposite direc- 
tion. 
strata near Iowa City, one of which has been described by Dr. 
C. hite as Strobilocystites Calvin’. Previous to this dis- 
covery it had been very generally supposed that the cystideans 
became extinct in the Upper Silurian ; certainly they did not 
persist very far into the Devonian. Nevertheless, last year, at 
another locality near Iowa City, I found the Lime Creek 
species, Productella dissimilis and Spirifera Whitney, in a thin 
bed of shale associated with plates of cystideans. The signifi- 
cance of this fact does not need to be stated: 
Then again, in 1876 and 1877, a number of Lime Creek 
species, including Productella dissimilis, were found associated 
with a peculiar fauna in some black shales below the limestones 
at Independence, Iowa. This fact was noted by me in a paper 
published in the Bulletin of United States Geological Survey, 
vol. iv, No. 3, in 1878. The Independence limestones have 
been referred by all geologists who have studied them, to the 
Hamilton, though Dr. Barris refers beds containing a simular 
fauna at Davenport, Iowa, to the Upper Helderberg. Acervularia 
profunda, A. Davidson, Phillipsastrea gigas and some other 
species that occur in the Independence limestones, are found in 
strata that have been referred to the horizon of the Upper 
Helderberg in Canada and Ohio. For a shell with a “de 
cidedly Carboniferous aspect,” Productella dissimilis has the 
somewhat questionable habit of always keeping company 1" 
Iowa with Lower Devonian types. ie 
In a note in this Journal for April, p. 311, Professor Williams 
withdraws the statement near the top of page 99, that Professor 
Worthen had referred the Lime Creek beds to the Kinderhook ; 
but the statement farther on, on the same page that “ the Lime 
Creek fauna is certainly more closely related to the fauna gf 
the Kinderhook group of Missouri, Indiana and Illinois than 
