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IOWA ACADEMY OP SCIENCE 
Weller found not only detaelied arms but also a few specimens 
in which the five arm-fans are still attached to the calyx. Two 
or three years later, in 1899, the late Professor Samuel Calvin 
found a very fine specimen retaining the arm-fans; this at 
present is the most perfect specimen in the University collection. 
The description of the complete crinoid by Weller gave Bather 
a clue to some similar arm-fans which had been collected in 
the Silurian on the island of Gotland in the Baltic Sea and 
which are in the Biksmuseum at Stockholm, Sweden. The Got- 
land arm-fans, together with a part of the Weller-Davidson col- 
lection and other material from J ones county, as well as a single 
arm-fan from St. Paul, Indiana, furnished the basis for Bather’s 
paper cited above. From this material six species were de- 
scribed; three from Gotland, two, including Weller’s species, 
from Jones county, and one from Indiana. It is interesting to 
note that only at these -widely separated localities have speci- 
mens of Petalocrinus ever been found. 
Several other fossils associated with Petalocrinus in Iowa are 
associated also with its relatives in Gotland. That the shore 
line along which this fauna lived and migrated in Silurian 
times was continuous from the Baltic across the present Atlantic 
to Iowa is very probable. 
It was while searching for specimens of Petalocrinus that the 
writer came upon a small area of residual soil unusually rich 
in fossils. In origin the soil is the ‘‘product of secular rock 
decay” as expressed by Calvin^ who has written an excellent 
description of the fossiliferous geest of Jones county. This par- 
ticular stony plot, its lean soil filled with chips and nodules of 
chert, proved a collector’s bonanza. Weathered-out corals, brach- 
iopods, crinoids, and other forms were common. The region, as 
far as known, had never yielded an arm-fan of Petalocrinus 
free from the stony matrix, but here scores of them lay on the 
surface, many of them practically perfect. 
The finding of so many weathered-out arm-fans inspired the 
hope that by close search some of the calyces might be secured 
and though none were found the search was not in vain for in 
all some thirty or forty dorsal cups of other small crinoids were 
obtained. They are well preserved although silieification has 
largely obscured the sutures between the plates; fortunately, a 
few individuals preserve these diagnostic features quite well. 
Uowa Geol. Surv., Vol. v (1895), pp. 62, 63. 
