Fauna of the Morrow Group 
197 
of opposite valve; plications similar to those of pedicle valve; 
the mesial portion of the surface of the valve anteriorly slightly 
flattened and rarely depressed into a faint sinus. 
Internally the structure is identical with that of the fore- 
going species. Shell structure finely punctate. 
Remarks. The varying aspect of the plications, depending 
upon the exfoliation of the specimens, is the same as that of 
H. hrentwoodensis , just described. From that species H. miseri 
may be distinguished by its more numerous and smaller plica- 
tions, its sub-ovate outline and proportionately greater width. 
Horizon and locality. Hale formation: East Mountain, Fay- 
etteville, Arkansas (Stations 136, 137, and 149). Brentwood 
limestone: near Fayetteville, Arkansas (Stations 134, 135, 140, 
and 153) ; Sawney Hollow, Oklahoma (Station 210). Kessler 
limestone: East Mountain, Fayetteville, Arkansas (Station 209). 
Morrow formation: near Ft. Gibson (Stations 301 and 303), 
Choteau (Stations 302 and 306), and Gore (Station 304), Okla- 
homa. 
Genus EUMETRIA Hall 
Eumetria vera (Hall) 
Plate XII, figures 14-~14b. 
1858. Retzia vera. Hall, Geol. Iowa, vol. 1, pt. 2, p. 704, pi. 27, fig. 3a. 
Kaskaskia limestone: Chester, Illinois. 
1894, Eumetria vera. Hall and Clarke, Int. to Study of Brack., pt. 2, 
pi. 37, figs. 8, 12. 
Chester limestone: Crittenden County, Kentucky. 
1894. Retzia vera. Keyes, Mo. Geol. Surv., vol. 5, p. 95. 
Kaskaskia limestone: Ste. Mary, Missouri, 
1895. Eumetria vera. Hall and Clarke, Pal. N. Y., vol. 8, pt. 2, pi. 51, 
figs. 36, 37. 
Chester group: Crittenden County, Kentucky. 
1909. Eumetria marcyi. Bassler, Va. Geol. Surv., Bull. No. 11-A, pi. 29, 
figs. 4, 5. 
1914. Eumetria vera. Weller, 111. State Geol. Surv., Mon. I, p. 444, pi. 
76, figs. 13-17. 
Chester group: Chester, Illinois. 
Three specimens of a Eumetria are present in the Morrow 
collections, all from the Brentwood limestone, and are referred 
with considerable confidence to this species. The form repre- 
sented is smaller than the average among this species but agrees 
