340 The American Geologist. J*^"*-^- i-'^s- 
four distinct and one or two indistinct ])licationj?, as in the 
Richmond grotip. In consequence, the phcations appear more 
angular. A single specimen of the Warren bed form was col- 
lected by Mr. J. F. Hammel at IMadison, Indiana, but the exact 
horizon from which it was collected is unknown. 
Catysyga lieadi may prove to be a very valuable horizon 
marker. It appears to have a very restricted vertical range. 
At Clarksville, Ohio, it has been collected, by Dr. George M. 
Austin, about fifteen feet below the horizon of Orthis insculpta. 
Lower down along Todds Fork, in Warren county, it has been 
collected by the same observer at the same level, near the hill 
tops about Hicks station. At Madison, Indiana, where the 
Hchcrtella insculpta horizon is unknown, Catyr:yga Jicadi is 
found fifty feet above the base of the Richmond. This must 
be somewhere near the top of the Lower Richmond. 
Dinorthis scovillei has so far not been found outside of the 
limits of Warren county, Ohio, although it is a well character- 
ized species. This is probably due to its very limited vert'cal 
range. On Longstreth's creek, west of Oregonia, it occurs at 
about the same level as Ganrocrinns iicalli, a short distance 
below the Dendrocrinns caduccns horizon, and a greater dis- 
tance below the Hehertella insculpta horizon. DalinancUa 
jugosa occurs farther down the creek. 
The type of Lingula vanhornci was found in the Lower 
Richmond, at Versailles, Indiana. 
The Middle Richmond. 
Dinorthis snbqnadrafa, Hchcrtella occidcntalis, Platystro- 
phia acntilirata, and Strophonicna vetusta (Str. Ulitexta of the 
Ohio survey) make their first appearance in the Middle Rich- 
mond and are therefore very serviceable in distinguishing the 
middle Richmond from the Lower Richmond in the areas in 
which Hehertella insculpta is absent. Dinorthis suhquadrata, 
Hchcrtella occidcntalis, and Platystrophia acntilirata occur al- 
so in the fossiliferous horizons of the Upper Richmond. Typi- 
cal specimens of Hehertella occidentalis occur along Elkhorn 
creek near Richmond, Indiana, twenty-seven feet below the 
Clinton. Forms with only a moderate depression along the 
middle of the dorsal valve occin- in the upper beds as far a*; the 
base of the Richmond. 
