KO. 2297. BRACHIOl'OD GENUS PLATYSTROPHIA—McEWAN. 421 



1^ miles south of Clark, etc., Kentucky. Liberty beds: Jefferson 

 County, Kentucky. 



Cotypes.— Cat. Nos. 40479, 65621, U.S.N.M. 



PLATYSTROPHU FOERSTEI AMPLA. new variety. 



Plate 46, figs. 13-16. 



This vai'iety differs from typical specimens of the species in being 

 decidedly ventricose and in having a hinge line shorter than the 

 width across the middle. 



Occurrence. — Richmond group: Arnheim formation: Lebanon, 

 Ohio. Waynesville formation: Long Run, near mouth of Tate's 

 Creek, and 1^ miles southeast of Thixton, Jefferson County, and 

 Sunset, Kentucky. Liberty beds: Ravine east of Floyd's Fork, 

 Jefferson Count}^, and Eastwood, Kentucky. Saluda-Whitewater 

 formation : Weisburg, Indiana. 



€oty pes. —Cat. Nos. 65635, 65636, 65637, U.S.N.M. 



PLATVSTROPHIA ATTENUATA, new species. 



Plate 46, figs. 1-4. 



Platystrophia acutilirata Cumings, Amer. Journ. Soi., ser. 4, vol. 15, 1915, p. 48, 

 fig. 25. 



This species is represented by small, transverse shells with low 

 folds and shallow sinuses, which become progressively wider toward 

 the front and are occupied by subequal plications. Most of the 

 specimens are thin, but some of them become decidedly convex. 



The hinge line generally forms the greatest width, but it may be 

 less than the width across the middle. The slopes of the brachial 

 valve are flatly convex; those of the pedicle valve flatly concave. 

 They are occupied by six to nine plications on the lateral slopes. 



Compared with Platystrophia acuminata, it is narrower and has 

 fewer plications. It is smaller and has a proportionately shorter 

 hinge than Platystrophia foerstH. It is very similar to Platystrophia 

 juveiiis but has fewer lateral plications than that species. This 

 species is scarcely distinguishable from some individuals belonging 

 to the Middle Trenton species Platystrophia amoena. It generally 

 has fewer plications, thinner valves, and stronger growth varices. 



Measurements. — 12 mm. along the hinge line, 13 mm. wide across 

 the middle, 9 mm. high, 5.8 mm. thick, 5.8 mm. sinal width, 4 mm. 

 sinal depth, 1 mm. fold height. 



Occurrence. — Richmond group: Waynesville formation: Oxford 

 and Warren County, Ohio; Simpson ville, Kentucky'; East Fork 

 White River, Indiana. 



Cotypes.—Csit. No. 41167, U.S.N.M. 



