ECHINODERMATA OF THE BRASSFIELD FORMATION 
11 
this point, the volutions were not preserved continuously. The 
columnals were approximately circular, with a moderately 
irregular margin. 
A second coiled column, (plate I, fig. 6) evidently belonging 
to the same species, was found recently, also in the upper part 
of the Brassfield limestone, 1 mile northeast of Wilberforce, and 
miles northeast of Xenia, Ohio. The exposure occurs east 
of the road to Clifton, on the northern side of the road to the 
Eastpoint school, along the upper part of the creek bed. Here 
large dissociated columnals of the same species are very common 
in the ferruginous layer, 2| feet below the base of the Dayton 
limestone. The coiled column found here has a length of 16.4 
cm. About three and a third volutions are preserved. Meas- 
uring from the larger toward the smaller end, the first volution 
has a length of 9.1 cm. ; the second, of 5 cm. ; the third, of 1.8 cm. ; 
and the remainder, of 0.5 cm. At the larger extremity the col- 
umnals have a diameter of 8 mm. ; at a distance of 7.8 cm. from 
the larger end this diameter is 6.5 mm.; 7.7 cm. from the second 
point the diameter equals 2.7 mm.; at its smallest extremity 
the diameter is only slightly more than 1.5 mm. These measure- 
ments suggest that the rate of decrease in the diameter of 
the column is more rapid nearer the smaller extremity. The 
margins of the columnals are badly weather worn but apparently 
were approximately circular, with a moderately irregular margin. 
The columnals are not of equal thickness. This is more 
readily noticeable in the larger columnals. Frequently narrower 
and thinner columnals alternate with thicker ones in such a 
manner as to suggest intercalation subsequent to the develop- 
ment of the larger columnals. This is a familiar feature among 
various genera of crinoids. Since both the larger and the inter- 
calated smaller columnals become thinner toward the lumen, 
it is evident that arftculation is secured by still smaller columnals, 
not readily seen in a view of the exterior of the complete column, 
though frequently still attached to the disarticulated larger 
columnals. The articulating surface of these articulating col- 
umnals, and the corresponding surface of that part of the larger 
columnals which surrounds the lumen, is radiately striated. 
