IETE IAG OCIIUM OS NAMORCAUBIOLIES (IN, SIZ.)) JEUNID) EN. INN 
AMERICAN FAUNA. 
Tue fossils described in the present paper were collected in 
Jones county, Iowa, by the junior author, Mrs. A. D. Davidson; 
the paper has been prepared by the senior author, Mr. Stuart 
Weller. The type specimens of the new species are deposited 
in Walker Museum at the University of Chicago. 
The fauna of the Niagara period in America has much in 
_ common with that of the Wenlock limestone in England. There 
are at least thirty" species common to the two faunas, and the 
relationship is such as to make it seem most probable that during 
that period a shore line along which the fauna lived reached 
continuously across the Atlantic Ocean of today, joining the 
east American to the British regions. The fauna of the Gotland 
limestone of Sweden also has numerous species common to the 
Wenlock limestone and the Niagara. Gontophyllum pyramidale 
and the species of Cvotalocrinus occur most abundantly in the 
Swedish beds though they are also present in the Wenlock lime- 
stone. The particular facies of the Silurian fauna containing 
Gontophyllum has not been generally recognized heretofore as 
American, and no crinoid has ever before been recorded which 
is at all closely related to Cvotalocrinus. 
Under these circumstances the discovery of a Silurian fauna 
in America containing specimens of Gonzophyllum which cannot 
be separated specifically from those of the Swedish beds, asso- 
ciated with a crinoid whose nearest ally is Cvotalocrinus is of 
extreme interest. Although it has seemed necessary to refer 
the crinoid not only to a distinct genus but even to a distinct 
family, it does not detract from the interest in the relationship 
of the faunas. It is well known that of all organisms which are 
preserved as fossils, none are more delicately adjusted to their 
? Phillips Manual of Geol., Part II., p. 122 (1885). 
166 
