Richmond Groiih of Cincinnati Anticline. — Focrstc. 335 
orthis fissicosfa as figured l)y ]^Ieek.* The area of the ventral 
valve is large, forming an angle of about seventy degrees with 
the plane separating the valves. The convexity of the ventral 
valve however is much less ; the shell has a flattened appear- 
ance anterior to the beak, and is often slightly depressed near 
the middle of the anterior margin, giving a slightly sinuous 
outline to this part of the shell. There is also a greater in- 
equality in size between the plications originating at the beak 
and those added later, so that the earlier formed plications are 
more conspicuous along the anterior half of the shell. The 
same form occurs in the Corryville bed at Cincinnati, Ohio, 
where it is identified as Plcctorthis dichotoina. Pkctorthis 
Ussicosta of Meek, from the Fairmount beds at Cincinnati is 
also identified as Plcctorthis dichotoma, by Schuchert.f The 
Corryville and Mount Auburn specimens just described may 
be easily distinguished from the Fairmount specimens now re- 
ferred to Plcctorthis dichotoma. 
The JVarrcn bed. 
The most characteristic brachiopod of the Warren bed is 
Dinorthis retrorsa: it is restricted, however, to a very short 
vertical range near the middle of the bed. Along the creek 
directly north of Lebanon, Ohio, a coarse limestone layer, four 
inches thick, occurs thirty-three feet above the Mount Auburn 
bed. The limestone layer is found at the north end of a large 
exposure on the west side of the creek, near the base. Three 
feet above this layer, Dinorthis retrorsa occurs associated with 
Leptaena rhomboidalis. Specimens of Dinorthis retrorsa were 
collected also eight feet above the limestone layer : the vertical 
range is therefore five feet. 
About seven miles northeast of Lebanon, Caesar's creek 
flows into the Little Miami river from the east. Almost di- 
rectly opposite. Lick run enters the river from the west. Lick 
run has its source in a spring located on the northeast side of a 
rise of land, formerly known as ]\Iorris hill, about two miles 
west of the river. The section along Lick rtin was used by 
professor Orton to determine the thickness of his Lebanon 
beds, which included both the Warren and the Richmond beds. 
The Mount Auburn bed is not exposed here. The large, quad- 
• Pal. Ohio, vol. i, 1873, pi. 8, fig. 6. 
t Synopsis of American Fossil Brachiopoda, p. 312. 
