Ulrich on Correlation of the Lower Silurian. 313 
ensis^ Diamesopora co77i77nmis^ and D. vazipeli^ are also very 
common at this horizon. 
Before Sfoing- farther I desire to mention two other interest- 
ing fossil horizons. The first, about 120 feet above low water 
mark, afforded fine examples of Tceniasterjlexuosa^ T.Jimbriata^ 
Palccaster Ji/iei^ Pa/ccastcr n, sp.^ Trmucleiis concejitricus^ T. 
belhdus and Scrpidites dissoluUis^ all species that are considered 
rare. Three feet below this bed another contained many spec- 
imens of fossil worms in excellent preservation which have 
been described by me under the names Protoscolex covi7igto7i- 
ensis^ P. ornatus and Eotrophonia setige7-a} Associated with 
these in extreme abundance were complete examples of an ex- 
ceedingly delicate jointed bryozoan {^A)-throstyh(s tctniis'). 
The second bed is about thirty feet above the star-fish layer, 
in a small run one-fourth of a mile south of Lewisburg, a 
suburb of Covington. Here several inches of the shale are 
crowded with graptolites belonging almost entirely to the 
species which I have named l7iocatdis arbiiscida. 
At the top of the Dekayella bed there comes in a large 
form of Callopora sigillaroidea. An occasional fragment of 
Constellaria Jlo/'ida var. p7-07ni7ie7is is also met with here, but 
in the succeeding fifty feet this strongly marked variety be- 
comes, at any rate at certain localities, very common. At 260 
feet above low water mark the majority of the bryozoa observed 
in the Dekayella bed reappear abundantly in a bed three or four 
feet thick. This brings us to the top of the sub-division which 
is marked by an increase in the limestones and in the sandy 
character of the strata. 
Little is known of the eastern and western extensions of this 
bed of shales, but there is scarcely any reason known to me why 
they should be found materially different from the Cincinnati 
section above described. To the south and beyond the Ken- 
tucky river some variation may be looked for, but this, it has 
been ascertained is not greater than has taken place in the 
southern extension of XIa. 
In Boyle, Washington, Mercer and other counties of Ken- 
tucky, the lower eighty feet or more, the same as at Cincinnati, 
consist mainly of soft shales, the limestones being thin and 
' Jour. Cin. Soc. Nat. Hist. vol. i, p. 187. 
