112 LAMELL1BRANCHS. 



at the free border in a little spine-like projection with curved- 

 up margin ; lines of growth fine on the body of the valve, but 

 becoming more distinct and irregular on the ears, where there 

 are rarely any denned radiating eostae. At a few distantly 

 separated intervals there are prominent imbricating laminae of 

 growth, showing the same digitate markings as the free bor- 

 ders of the shell. In the right valve the surface markings are 

 somewhat like those of the other valve, but much more obscure, 

 excepting on the anterior wing, where there are a few more 

 distinct radiating costae. ( Meek.) 



Horizon and localities Upper Carboniferous, Upper Coal 

 Measures: Kansas City. 



Aviculopecten coxanus MEEK & WORTHEN. 



Aviculopecten coxanus Meek & Worthen, 1860: Proc. Acad. Nat. Sci., 



Phila., p. 453. 

 Aviculopecten coxanus Meek & Worthen, 1866: Geol. Sur. Illinois, vol. II, 



p. 326, pi. xxvi, figs. 6a-b. 

 Aviculopecten coxanus Meek, 1872: U. S. Geol. Sur. Nebraska, p. 196, pi. 



ix, figs. 2a-b. 

 Aviculopecten coxanus Keyes, 1888: Proc. Acad. Nat. Sci., Phila., p. 232. 



Shell like A. occidentalis Shumard, but very much smaller, 

 thinner, and proportionally longer; ribs larger and further 

 apart ; posterior slope considerably longer than the anterior. 



Horizon and localities. Upper Carboniferous, Upper Coal 

 Measures : Kansas City. 



Aviculopecten? interlineatus MEEK & WORTHEN. 



Plate xlii, fig. 6. 



Aviculopecten interlineatus Meek & Worthen, 1860: Proc. Acad. Nat. Sci., 



Phila., p. 454. 

 Aviculopecten interlineatus Meek & Worthen, 1868: Geol. Sur. Illinois, vol. 



IE, p. 329, pi. xxvi, figs. 7a-b. 

 Aviculopecten? interlineatus White, 1884: Geol. Sur. Indiana, 13th Ann. 



Rep., pt. ii, p. 145, pi. xxx, fig. 9. 



A small subcircular form, with long straight hinge-line; 

 and characterized especially by prominent, rather distant con- 

 centric ridges. 



Horizon and localities. Upper Carboniferous, Upper 

 Coal Measures: Kansas City. 



