320 
Aug. F .^-Foerste 
Dinorthis ulrichi, sp. nov. 
(Plate VII, Figs. 7, A, B,C.) 
This species closely resembles Dinorthis subquadrata in almost | 
every feature, exterior and interior. Dinorthis ulrichi differs j 
chiefly in the more conspicuous flattening of the pedicel valve, j 
the convexity at the umbo being less prominent and being con- i 
fined to the immediate vicinity of the beak. In some specimens 
the median part of the valve is depressed anteriorly so as to form I; 
a broad, shallow sinus. The shell frequently is wider posteriorly } 
than across the middle, producing a more angular outline, postero- l| 
laterally, than in most specimens of Dinorthis subquadrata. The |i 
radiating plications usually are coarser than in that species, but 
individual specimens may be selected which do not differ in this I 
respect. The muscular impressions of the pedicel valve are |! 
similar in form but tend to be relatively smaller in size, occupy- i 
ing slightly less than half the length of the valve. f 
Compared with Dinorthis meedsi, Winchell and Schuchert, |i 
Dinorthis ulrichi is much larger, the pedicel valve is more strongly 1: 
flattened, the shell is less suborbicular in outline, and the plica- j 
tions usually are coarser. '| 
Geological position. The types are from the upper part of the >1 
Paris bed on the C. H. Bowyer farm, northeast of Becknerville, 
in the western part of Clark county, Kentucky. The exposures | 
are on the eastern side of the creek crossing the farm in a southerly i 
direction. The Flanagan chert is exposed west of the creek j 
toward the northern part of the farm. Associated in the same |i 
layers with Dinorthis ulrichi are Flebertella frankfortensis, Rhyn- |! 
chotrema incequivalve, and Strophomena vicina. It is found at 
the same geological horizon, also at Flanagan, in Clark county, i 
and in the railroad cut in the northeastern part of Paris, in Bourbon i 
county, Kentucky. 
!. 
Dinorthis carleyi — insolens, var. nov. | 
(Plate VII, Fig. g.) ( 
A variety of Dinorthis carleyi occurs at various localities in j; 
Ohio and Indiana at the base of the Upper or Blanchester division j! 
of the Waynesville bed which differs from the typical form of the | 
species only in having somewhat wider and flatter plications. i 
