NO. 2297. BRACMIOPOD GENUS FLATYSTROFHlA—AlcEWAN. 447 



Figs. 6-8, PlatystropMa preponderosa, new species, p. 427. 



6. Pedicle valve. This figure shows a moderately deep sinus. 



7. Brachial valve with a moderately elevated fold. 



8. Cardinal vieAV showing the globos? form. 



Trenton group (Tatheys limestone), 2 miles west of Nash^•ille, Tennessee. 

 Figs. 9-12. PlatystropMa ponderosa auhurnensis Foerste, p. 428. 



9. Cardinal view showing the shortened hinge-line and globose form. 



10. Brachial valve. The Avell-marked growth lines are characteristic. 

 Majsville group (^ilouut Auljurn), Cincinnati, Ohio. 



11. Pedicle valve. 



Maysville group (Mount Aulmrn) Oldham County, Kentucky. 



12. Cardinal view of an immature specimen. 

 Maysville group (Mount Au])urn), Madison, Indiana. 



Plate 50. 



All figures on this plate are natural size. 

 Figs. 1-3. Platystrophia fenivalensis, new species, p. 428. 



1. Interior of pedicle valve showing the deep muscle scar. 



2. Pedicle valve. The coarse plications at the beak split into striae as they 



approach the margins. 



3. Brachial valve. The low fold is typical. 



The outer margins of these specimens are broken away. 



Richmond group (Fern vale limestone), Old Quarry southeast of Regenhardts 

 Quarry at the north Avest edge of Cape Oirardeau, Missouri. 

 Figs. 4-7. PlatystropMa ponderosa, variety. 



4. Cardinal A'iew. The figure illustrates the short hinge and globose form. 



5. Brachial vah^e showing curved plications next to the cardinal angles. (Same 



specimen as fig. 4.) 

 Richmond group (Arnheim formation), near Bakers, Tennessee. 



6. Pedicle valve showing the broad round sinus. 



Richmond group (Arnheim) east of Long Run Sta., Jefferson County, Ky. 



7. Pedicle valve of a mutation with seven plications in the sinus. 



Richmond group (Arnheim formation), Long Run, south of Eastwood, Ken- 

 tucky. 

 This type of shell seems to he confined to the Arnheim member of the Richmond 

 group. 

 Figs. 8-11. PlatystropMa, species. 



8. Pedicle valve showing the broad shallow sinus. 



9. Cardinal view. The extended hinge line is characteristic. 



10. Brachial valve. The figure illustrates the low, broad fold . 



11. Anterior view. The even convexity of the pedicle valve is shown. 

 Maysville group (Bellevue member), Madison, Indiana. 



12. Cardinal view of a subquadrate mutation. 



13. Brachial valve of the same specimen. 



14. Pedicle valve of the same type of shell. 



15. Lateral view of the same specimen. 



Maysville group (Mount Auburn), Cincinnati, Ohio. 



Plate 51. 



Figs. 1-5. PlatystropMa ponderosa, variet}'. 



1. Brachial valve showing the loss of elope on the left side of fold. 



Richmond group (Arnheim formation), on Floyd's Fork, 1 mile northeast of 

 Seatonville, Kentucky. 



2. Brachial valve of a decidedly asymmetrical form. 



