Fauna of the Morrow Group 
235 
1911. Worthenia tabulata. Raymond, Penn. Topog. and Geol. Surv. 
Comm., Rep. for 1908-10, pi. 5, fig. 2. 
Brush Creek limestone: Donohoe, Pennsylvania. 
An incomplete external mold from the Kessler limestone is 
referred to this species with considerable confidence. Portions 
of eight volutions are represented and in shape, surface mark- 
ings, and angularity of the whorls, the material at hand corre- 
sponds in every particular to the figures and descriptions of 
the typical members of Conrad’s species. 
Horizon and locality. Kessler limestone: East Mountain, 
Fayetteville, Arkansas (Station 209). 
Genus EUCONOSPIRA Ulrich 
Euconospira arkansana n. sp. 
Plate XV, figure 25. 
Description. Shell below medium size, regularly conical in 
shape, somewhat broader than high, base gently convex; volu- 
tions five or six in number, fiattened on the upper or visible 
slope, the last one distinctly angular around the periphery, and 
slightly convex below; umbilical region gently concave, um- 
bilicus small and probably quite shallow ; band narrow, concave, 
grooved, visible on all the volutions, situated between two 
sharply elevated lines, the lower one of which forms the peri- 
phery of the whorls ; aperture not well shown in any of the speci- 
mens at hand; surface ornamented by about nine, somewhat 
irregularly spaced, revolving costae crossed by slightly fainter, 
more closely spaced, oblique and gently curved, transverse lines 
which make the costae appear as discontinuous series of small 
nodes; below the angle the under side of the body whorl bears 
about twelve fine revolving costae crossed by very faint obscure 
lines of growth. 
Height of an average specimen, 8.5 mm. ; breadth, 9.8 mm. ; 
apical angle, 70°. 
Remarks. In comparison with E. turhiniformis (M. & W.) 
which shell this form closely resembles in shape, it is charac- 
terized by the much smaller size of the adult individuals and 
the smaller number of revolving costae on each volution. 
Horizon and locality. Brentwood limestone: near Fayette- 
ville, Arkansas (Stations 134 and 135). Morrow formation: 
near Choteau, Oklahoma (Station 302). 
