Weno and Pawpaw Formations 63 



The Pawpaw and Grayson each has a considerable assemblage of small 

 pyritic and limonitic pelecypod casts. 



TABULATION OF KNOWN PYRITE OR LIMONITE PELECYPODS IN THE 

 WASHITA PYRITE FAUNAE 



Duck Creek Denton Pawpaw Grayson 



Species marl marl clay marl 



Area 1 1 1 1 



Nucula 1 1 1 1 



*Leda . . 1 1 



"Corbula .. 1 1 



*Plicatula 1221 



*Barbatia . . . . ". . 1 



*Isocardia (?) .. .. .. 1 



*Remondia (?) .. .. 1 1 



Lima 1 1 2 1 



GASTROPODA : 



As may be seen in the following table, a fauna of small gastropods is 

 a feature of the pyrite and limonite fossils in these four formations. In 

 the Duck Creek marl these small limonite gastropods are the most con- 

 spicuous element of the fauna. 



TABULATION OF WASHITA LIMONITE AND PYRITE GASTROPODS 



Duck Creek Denton Pawpaw Grayson 



Species marl marl clay marl 



Natica 1 1 1 1 



Cinulia 1 1 1 1 



*Cerithium 1 . . . . 1 



Turritolla 1 .. 1 2 



*Gyrodes 1 .. .. 1 



Turbo 1 .. 1 1 



Lunatia 2 .. 1 



*Nerinea 2 . . 1 



*Anchnra . 1 



OTHER COMPONENTS: 



Small corals (Trochosmilia, Placosmilia) occur in the Duck Creek and 

 Pawpaw formations, and probably in the Denton and Grayson. There is 

 a notable abundance of small sharks (Lamna, Oxyrhina, Ptychodus) in 

 the Pawpaw, where teeth, vertebrae, plates, skin and bones are found ; 

 the same fossils are found less abundantly in the other formations in 



