LAMELLIBRANCHS. 115 



Enchondria neglecta (GEINITZ) 

 Pecien neglectus Geinitz, 1866 : Garb, und Dyas in Nebraska, p. 56, tab.* 



ill, fig. 7. 



Aviculopecten neglectus Meek, 1867 : Am. Jour. Sci., (2), vol. XLV, p. 64. 

 Avieulopecten neglectus Meek & Worthen, 1873: Geol. Sur. Illinois, vol. V, 



p. 589, pi. xxvi, figs. 7a-b. 



Enchondria neglecta Meek, 1874 : Am. Jour. Sci. , (3), vol. VII, p. 445. 

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



A small form like an Entolium in general appearance, but 

 with large ribbed ears, and crenulated cardinal margin. 



Horizon and localities. Upper Carboniferous, Upper Coal 

 Measures: Kansas City. 



Aviculopinna americana MEKK. 



Avicula pinnceformis Geinitz, 1866: Carb. und Dyas in Nebraska, p. 31, 



tab ii, fig. 13. (Not A. pinnceformis, Geinitz, 1857.) 



Aviculopinna americana Meek, 1867 : Am. Jour. Sci., (2), vol. XLIV, p. 282. 

 Aviculopinna americana Meek, 1872: U. S. Geol. Sur. Nebraska, p. 197, 



pi. ix, figs. 12a-d. 



Shell small, compressed, with the slender elongated form 

 of some of the Carboniferous species of Pinna ; cardinal and 

 ventral margins generally nearly straight (the latter being the 

 more convex in outline) and converging gradually from behind 

 to the rather obtusely pointed anterior extremity ; posterior 

 side truncated, rounding to the base, and intersecting the ' 

 posterior extremity of the hinge very nearly at right angles ; 

 a little sinuous just below the extremity of the hinge. Cardi- 

 nal margin so slightly convex in outline as to appear quite 

 straight, very nearly equaling the greatest length of the valves, 

 and provided with a well-defined marginal ridge, which narrows 

 to a mere line, or dies out before reaching the beaks, and 

 widens very gradually to the posterior extremity. Beaks nearly 

 or quite obsolete, extremely oblique, and very slightly behind 

 the very narrow, obtusely pointed anterior extremity. Surface 

 with two or three broad, nearly obsolete radiating ridges on the 

 posterior dorsal region, and ornamented by numerous slender, 

 very regularly disposed and abruptly elevated lines of lamellae, 

 much narrower than the space between and curving gracefully 



