118 LAMELLIBBANCHS. 



Similar to M. swallowi but inequivalve, very much larger, 

 heavier, and with the beaks incurved; surface with somewhat 

 imbricated lines of growth. 



Horizon and localities. Upper Carboniferous, Upper Coal 

 Measures : Kansas City. 



Myalina perattenuata MEEK&HAYDEN. 



Myalina perattenuata Meek & Hayden, 1858: Trans. Albany Institute, 



vol. IV, p. 77. 

 Myalina perattenuata Meek & Worthen, 1873: Geol. Sur. Illinois, vol. V, 



p. 582, pi. xxvi, fig. 11. 



Shell rather small, with sharp, protruding beaks, and 

 broadly rounded posterior margin. 



Horizon and localities. Upper Carboniferous, Upper Coal 

 Measures: Kansas City. 



Myalina angulata MEEK & WORTHEN. 



Myalina angnlata Meek & Worthen, 1860: Proc. Acad. Nat. Sci., Phila., 



p. 455. 

 Myalina angulata Meek & Worthen, 1866: Geol. Sur. Illinois, vol. II, p. 



300, pi. xxiii, figs. 7a-b. 



Shell quite large, with extended, compressed beaks, and 

 subalate dorsum. 



Horizon and localities. Lower Carboniferous, Kaskaskia 

 limestone : Ste. Mary ( Ste. Genevieve county ). 



Myalina subquadrata SHUMARD. 

 Plate xliv, figs, la-b and 2a-b. 



Myalina subquadrata Shumard, 1855 : Geol. Sur. Missouri, Ann. Kept., 



p. 207, pi. C, fig. 17. 

 Myalina subquadrata Geinitz, 1866: Carb. und Dy as in Nebraska, p. 27, 



tab. iii, figs. 25-26. 

 Myalina subquadrata Meek, 1872: U. S. Geol. Sur. Nebraska, p. 202, pi. 



iv, fig. 12; and pi. ix, fig. 6. 

 Myalina subquadrata White, 1884: Geol. Sur. Indiana, 13th Ann. Kept., 



pt. ii, p. 140, pi. xxix, figs. 1-2. 



Shell large, massive, oblong, somewhat higher than long, 

 winged above the posterior umbonal slope. Hinge-line straight, 

 as long as the greatest length of valves; below regularly 

 curved ; anterior border somewhat concave above ; posterior 

 margin nearly straight, vertical. Beaks terminal. Cardinal 



