LAMELLIBBANOHS. 121 



Horizon and localities. Upper Carboniferous, Upper Coal 

 Measures: Kansas City. 



The bivalve under consideration was originally described 

 from the Appalachian region, where it appears to be rather 

 widely distributed through Pennsylvania, West Virginia and 

 Ohio. It has only recently been recognized west of the Mis- 

 sissippi river. The western shells are somewhat larger than 

 those from the eastern localities, but do not differ essentially 

 from the typical forms of the genus. Meek's type specimen 

 was a good example, showing the specific characters perfectly. 



Macrodon sangamonensis ? WOBTHBN. 



Platexlvi, fig. 2. 



Macrodon sangamonensis Worthen, 1890: Geol. Sur. Illinois, vol. VIIL, p. 

 123, pi. xxi, tig. 3. 



Similar to M. obsoletus, but smaller, and with radiating ribs. 



Horizon and localities Upper Carboniferous, Upper Coal 



Measures: Kansas City. 



Nucula parva MCCHBSNEY. 



Nucula parva M.cChesney, 1860: Desc. New Pal. Foss., p. 54. 

 Nucula parva McChesney, 1867 : Trans. Chicago Acad. Sci., vol. I, p. 39, 



pi. ii, figs. 8a-c. 

 Nucula parva Meek & Worthen, 1873: Geol. Sur. Illinois, vol. V, p. 589, 



pi. xx vi. figs. 8a-b. 



Nucula purvn Keyes, 1888: Proc. Acad. Nat Sci., Phil., p. 250. 

 Nucula parva Keyes, 1891 : Johns Hopkins Univ. Circulars, vol. XI, p. 29. 



A very small shell, differing from N. ventricosa, not only 

 in size, but in the long, posterior slope, and marked concentric 

 lines of growth. 



Horizon and localities Upper Carboniferous, Upper Coal 

 Measures : Kansas City. 



Nucula ventricosa HALL. 



Plats xlv, figs. 3a-b. 

 Nucula ventricosa Hall, 1858: Geology Iowa, vol. I, p. 716, pi. xxix, figs. 



4, 5a-b. 

 Nucula ventricosa Meek, 1872: U. S. Geol. Sur. Nebraska, p. 204, pi. x, 



figs. 17a-c. 

 Nucula ventricosa White, 1882 : Geol. Sur. Indiana, Kept, for 1881, p. 



371, pi. xlii, figs. 9, 10. 



Nucula ventricosa White, 1884: Geol. Sur. Indiana, Kept, for 1883, p. 

 146, pi. xxvii, figs. 9, 10. 



