438 rROCEEDINGii OF THE NATIONAL MUSEUM. 



PLATYSTROPHIA CYPHA BELLATULA, new variety. 



Plate 47, figs. 28-30. 



In the Waynes ville formation of Ohio and Kentucky there is a small 

 variety of PlaiystropJiia cyplia with six, seven, or eight plications on 

 the lateral slopes. This variety has many characteristics in common 

 with Platystropliia unicostata. It is smaller and shorter than that 

 species, and has somewhat narrower plications on the lateral slopes. 



Measurements. — 25.2 mm. along the hinge line, 21.5 mm. wide 

 across the middle, 14 mm. high, 17 mm. thick, 9.5 mm. sinal width, 

 13 mm. sinal depth, 4.5 mm. fold depth. 



Occurrence. — Richmond group: Waynesville formation; Waynee?- 

 viUe and ClarksviUe, Ohio; Westport, Kentucky. 



Cotypes.~Ci\t. No. 66021, U.S.N.M. 



PLATYSTROPHIA WALLOWAYI Foerste. 



Plate 45, figs. 5-8. 



Platystrophia wallowaifi Foerste, Ohio Naturalist, vol. 1-, J 912, p. 453, pi. 

 22, fig. 6. 



This represents a globose form with a hinge Ime somewhat shorter 

 than the width across the middle, a high, broad, rounded fold and 

 broad deep sinus. The brachial valve is strongly convex. The pedicle 

 valve is not as deep as the brachial valve; it is convex next to the 

 sinus, but becomes slightly concave toward the cardinal angles. 

 There are usually four plications on the fold and three in the sinus 

 but in some s])ecimens there are five or more plications on the fold 

 and fom* or more in the sinus. There are usually 9 or 10 plications on 

 the lateral slopes. Mature specimens have strong growth lines. 



Measurements. — 19 mm. along the hinge line, 22.6 mm. wide below 

 the middle (greatest width), 17.3 mm. high, 17.2 mm. thick, 13.7 

 mm. sinal width, 11.3 mm. sinal depth, 6.7 mm. fold height. 



Occurrence. — Richmond group: Arnheim formation: Walloway 

 Creek, near Boston, Bardstown, etc., Kentucky; Southeastern Indi- 

 ana. 



Plesioty pes. —C^t. Nos. 39043, 65981, U.S.N.M. 



EXPLANATION OF PLATES. 



Pl.ATK 42. 



All figures on this plate are natural size. 

 Figs. 1, 2. Platystrophia uniplicate. new species, p. 405. 



1. Pedicle valve showing one plication in the sinus. 



2. Brachial valve. The low fold bearing two plications is typical (same si^ecimen 



as fig. 1). 

 Trenton limestone near Lake ("hamplain. New York. 



