MEDINAN, NIAGARAN, AND CHESTER FOSSILS 
81 
low and crowded, resembling those of Coelocaulus oehlerti Ulrich^^ 
in their crowded conditions, but the spire is much shorter. 
(Plate XV, fig. 5.) 
In a few specimens the slit-band is traversed by 3 revolving 
striae or lines of elevation, the two lateral ones lying closer to 
the median striation than to the striae forming the lateral mar- 
gins of this band. 
A similar form, but only 6 mm. in length and with 5 or 6 
volutions, was found by Professor W. H. Shideler of Miami 
University at the exposure of the Belfast bed 2 miles south of 
West Union, on the Beasley Fork road. The typical Belfast 
bed here is 1 foot thick, and the specimens of Hormotoma are 
common about 4 feet beneath. 
No Silurian species of Hormotoma with such a strongly Ordovi- 
cian facies as that presented by the specimens here described 
are known. Loxonema suhulata Conrad may be a Hormotoma, 
but it presents an aspect quite different from that of the Center- 
ville specimens. 
Hormotoma centervillensis Sp. nov. 
Plate XV, fig. 7 
Spire with an apical angle of about 20° and with sutures form- 
ing an angle of about 70° with the vertical axis of the shell. The 
base of the shell attains a maximum diameter of 11 mm. Five 
volutions occur in a length of 26.5 mm., and it is estimated that 
the 'original length of the shell equalled about 36 mm., and that 
within this length there were 10 or 11 volutions. 
Compared with Hormotoma trilineata the volutions are more 
oblique and more elongate. No tendency toward angulation 
of the volutions along its periphery, where the slit-band is lo- 
cated, is noticed. The surface here is evenly convex. The mar- 
gins of the slit-band are indicated by relatively faint, and very 
narrow lines. The area of the band itself is flat, and shows no 
evidence of trilineation. 
-2 Idem., pi. 70, figs. 61, 62. 
