40 
AUG. F. FOERSTE 
radiating plications, probably identical with Orthis dinorthis 
Foerste.'"^ These fossils suggest Brassfield afh.nities. Recently 
Prof. W. H. Shideler, of Miami University, found specimens of 
Whitfieldella and other fossils having a Silurian aspect in argil- 
laceous strata immediately beneath the typical Belfast bed on 
Beasley Fork southeast of West Union, Ohio. Their horizon 
probably is the same as that of the Montgomery county speci- 
mens provisionally referred to the Edgewood. 
In Montgomery county, Ohio, the upper part of the Brassfield 
limestone frequently contains interbedded layers of richly fossili- 
ferous clay. Many fossils occur here which are unknown in 
the underlying parts of the Brassfield limestone, though the 
more commonly known fossils occur at both horizons. In 
general, the Brassfield limestone of Ohio, Indiana, and Kentucky 
appears to correspond to the Manitoulin dolomite of southern 
Ontario; but the upper, more ferruginous part may correspond 
approximately to the Cabot Head shale, which, in southern 
Ontario, is the horizon for Rhinopora verrucosa, while the genus 
Brockocystis appears limited to the Manitoulin limestone in that 
province. 
The name Beaver town marl was not intended to designate 
the richly fossiliferous clay forming the upper part of the Brass- 
field section or included in the latter locally, but it was used to 
designate a soft, very fine grained deposit, an argillaceous lime- 
stone, readily disintegrating under the influences of weathering, 
and not a marl in any sense of the term. The term was first 
used in 1885,'^ and several species, including Platystrophia re- 
versata, Ctenodonta minima, Liospira affinis, Cyclora alta, Bellero- 
phon exiguus, Orthoceras inceptum, and the problematical species 
designated as Zygospira modesta and Trochonema nanum, were 
described from this horizon. The large crinoid beads found 
in this stratum were of the same type as those found in the upper 
part of the Brassfield limestone, and the Beavertown marl is 
5 Foerste, A. F., Fossils of the Clinton group in Ohio and Indiana: Ohio Geol. 
Survey., voL 7, 1893, pL 31, fig. 4. 
® Foerste, A. F., The Clinton Group of Ohio: Denison Univ. Bull. Sci. Lab., vol. 
1, 1885 p. 74. 
