670 C. SCHUCHERT DEVONIAN OF OKLAHOMA 



bryozoans. RhipidomeUa museulosa (Hall), *Leptcena rhomboidalis ven- 

 tricosa (Hall). *Leptostrophia orisTcania Clarke. Stropheodonta vascu- 

 laris Hall. 8troph4meUa sp.. *Eatonia peculiaris ( Conrad "i. *Pletho- 

 rhyncha prwspeciosa Scliucliert. Delthyris raricostus (Conrad) ?, *8piri- 

 fer arenosus (Conrad). *&. murchisoni (Castelnau) , 8. n. sp. in line to 

 n. divaricatU8 s Meristella lata Hall. *Rensselwria marylandica Hall. 

 Orth onychia tortuosum (Hall), Dalmanites {Odontocephalus) . 



An easily seen erosional unconformity is shown in Sallisaw Creek. 

 A long land interval. All of Helderbergian strata absent and all of Upper 

 Silurian. 



Middle Silurian. 



Saint Clair marble or Sallisaw marble of Taff. At least 60 feet of a 

 massive, coarsely crystalline limestone is exposed in the marble quarry, 

 and Taff states that the total thickness exceeds 200 feet. Almost no 

 bedding planes are seen in the quarry, and here were collected a speci- 

 men each of Chyroceras elrodi Hall and Protokionoceras medulla re Hall? 

 Taff lists nine other species from the upper part of the Saint Clair that 

 indicate the time of this portion to be later Middle Silurian. 



