Fauna of the Morrow Group 
227 
Aviculopecten sp. 
Plate XV y figure 16. 
From the same locality in the Kessler limestone as that which 
furnished the species just described was obtained an internal 
cast of a shell with the same general shape but differing from 
it in important details. The hinge-line is proportionately 
shorter, the ears smaller, the beak converging upward less 
acutely, and the whole valve less convex. The external orna- 
mentations of this form are unfortunately not known and the 
internal cast is smooth except for faint concentric growth lines 
and a suggestion of radiating striae. It is probably a cast of 
another undescribed Aviculopecten. 
HoHzon and locality. Kessler limestone: East Mountain, 
Fayetteville, Arkansas (Station 209). 
Genus DELTOPECTEN Etheridge 
Deltopecten occidentalis (Shumard) 
Pecten occidentalis. Shumard, 1st and 2nd Repts. Geol. Surv. Mo., 
p, 207, pi. C, fig. 18. 
Coal Measures: Near Plattsburg, Clinton County, Missouri. 
Pecten Clear elandicus. Swallow, Trans. St. Louis Acad. Sci., vol. 
1, p. 184. 
Permian: Valley of South Cottonwood, Kansas. 
Pecten occidentalis. Newberry, Ives’s Colo. Expl. Exped., p. 128. 
Coal Measures: Banks of the Stranger, above Easton, Kansas. 
Aviculopecten ?. Meek and Hayden, Pal. Upper Mo., 
p. 50, pi. 2, fig. 10. 
Permian: Near Chapman’s Creek, 18 miles above Ft. Riley, Kansas. 
Aviculopecten occidentalis. Meek and Worthen, Geol. Surv. 111., vol. 
2, p. 331, pi. 27, figs. 4-5a. 
Upper Coal Measures: Saline Creek, Gallatin County, Illinois. 
Pecten Missouriensis ?. Geinitz, Carb. und Dyas in Nebr., p. 35, 
tab. 2, fig. 18, 
Nebraska City, Nebraska. 
Aviculopecten occidentalis. Meek, U. S. Geol. Surv. Nebr., p. 191, 
pi. 9, fig. 10. 
Upper Coal Measures: Rock Bluff, Bennett’s Mill, Wyoming, and 
Nebraska City, Nebraska; Illinois; Missouri; Iowa; Kansas; 
Kentucky. 
Coal Measures: Black Hills, Dakota. 
Aviculopecten occidentalis. White, Powell’s Rep. Geol. Uinta Mts., 
p. 90. 
Lower Aubrey group: Two miles above Belleview, Utah. 
1855. 
18*58. 
1861. 
1864. 
1866. 
1866. 
1872. 
1876. 
