Fauna of the Morrow Group 
223 
1875. Aviculopecten ( Streblopteria ?) hertzeri. Meek, Pal. Ohio, vol. 2, 
p. 330, pi. 19, figs. ISa-c. 
Lower Coal Measures: Newark, Ohio. 
1887. Aviculopecten hertzeri. Herrick, Bull. Sci. Lab. Den. Univ., vol. 2, 
p. 25, pi. 1, figs. 5, 10. 
Coal Measures: Flint Ridge, Ohio. 
1900. Aviculopecten hertzeri. Beede, Univ. Geol. Surv. Kans., vol. 6, 
p. 121, pi. 13, figs. 8, 1, lb. 
Upper Coal Measures: Topeka, Kansas. 
1911. Aviculopecten hertzeri. Mark, Bull. Sci. Lab. Den. Univ., vol. 16, 
p. 312, pi. 10, fig. 3. 
Mercer limestone: Somerset, Ohio. 
Only one specimen of this form has been found in the forma- 
tions of the Morrow group and it is incomplete in the cardinal 
region; it is referred with confidence to this species on account 
of its distinctive shape and surface markings. 
Horizon and locality. Kessler limestone: near Brentwood, 
Arkansas (Station 144). 
Aviculopecten talboti Worthen ? 
1884. Aviculopecten talboti. Worthen, Bull. No. 2, 111. State Mus. Nat. 
Hist., p. 21. 
St. Louis limestone (oolite beds) : Monroe County, Illinois. 
1890. Aviculopecten talboti. Worthen, Geol. Surv. 111., vol. 8, p. 114, pi. 
22, figs. 11, 11a. 
St. Louis limestone (oolite beds) : Monroe County, Illinois. 
A single left valve, nearly perfect, from the Hale formation 
corresponds exactly with Worthen’s descriptions and figures of 
this species but when compared with other material from the 
Monroe County locality minor variations may be noted. The 
hinge-line is proportionately slightly shorter in the Arkansas 
form, while the Illinois specimens are longer than high and 
have somewhat stronger surface markings. 
Horizon and locality. Hale formation: East Mountain, Fay- 
etteville, Arkansas (Station 136). 
Aviculopecten halensis n. sp. 
Plate XV, figure 17. 
Description. Shell small, sub-oval in outline exclusive of the 
ears, length a little greater than height, hinge-line somewhat 
shorter than length of valve below, ears comparatively large 
and well-defined; left valve moderately convex, ears defined by 
