DESCRIPTION OF SPECIES 233 



Genus Lima Brugueire 



Lima retifera Shumard 

 PI. XIII, fig. 10 



1858 Lima retifera. Shumard, Trans. St. Louis Acad. Sci., Vol. 1, p. 214. 

 Coal Measures: Valley of Verdigris, Kansas. 



Remarks. Lima retifer is another form of wide geographic and 

 stratigraphic distribution which is common in the middle and upper 

 Pottsville formation of Ohio, especially in the Lower Mercer and 

 McArthur members. A considerable number of individuals have 

 been examined, many in an excellent state of preservation, and no 

 marked variations from the species as ordinarily interpreted have been 

 noted. The species is recorded as high as the upper Conemaugh forma- 

 tion in this State. 



Horizon and locality. Widely distributed throughout the Lower 

 Mercer and McArthur members, c. 



Genus Placunopsis Morris and Lycett 



Placunopsis ? recticardinalis Meek 

 PL XII, fig. 19 



1875 Placunopsis recticardinalis. Meek, Pal. Ohio, Vol. II, p. 331, PI. 19, Fig. 12. 



Coal Measures: Flint Ridge and Putnam Hill, Ohio. 

 1887 Placunopsis recticardinalis. Herrick, Bull. Den. Univ., Vol. 2, p. 43, PI. 4. 



Fig. 11. 



Coal Measures: Flint Ridge, Ohio. 



Meek's description. "Shell truncato-suboval or subquadrilateral, 

 slightly oblique, with length and breadth nearly equal; cardinal margin 

 straight, not quite equaling the greatest breadth of the valves; lateral 

 margins almost straight and parallel, meeting the hinge at nearly right 

 angles, and rounding regularly to the rounded ventral edge; upper 

 valve depressed, most convex between the beak and central region; 

 beak small, depressed, and but slightly projecting beyond the cardinal 

 margin, near the middle of which it is placed with scarcely perceptible 

 obliquity; surface showing fine, obscure lines, and a few stronger marks 

 of growth, with faint traces of radiating striae, and an entirely dis- 

 tinct set of regular, transverse, waved or arched, parallel, little linear 

 ridges or costae, which appear to have resulted from the markings of 

 the surface of the object upon which the shell had grown; lower (right ?) 

 valve unknown." 



