Weno and Pawpaw Formations 123 



OSTREA (ALECTRYONIA) QUADRIPLICATA Shumard 



1860: Ostrea quadriplicata Shumard, Trans. St. Louis Acad. Sci., vol. 1, p. 608. 

 1879: Ostrea quadriplicata White, llth Ann. Kept. U. S. G. and G. Surv., Terr., pp. 275- 



276, pi. 5, fig. 6a. 

 1920: Ostrea quadriplicata Adkins and Winton, Univ. Texas Bull. 1945, p. 60, pi. 16, 



figs. 6-10. 



This species has not been seen above the Mainstreet limestone, where 

 it is rare, or below the Denton marl. It is abundant at the top of the 

 Denton marl, with Ostrea carinata and Gryphea washitaensis ; and at the 

 Weno-Pawpaw contact in the Quarry limestone, with Ostrea carinata. 

 Gryphea washitaensis and cidarid spines. 



This species is not known in South Central Texas, but is abundant near 

 El Paso in subdivision 6 (equivalent of Weno-Pawpaw). 



EXOGYRA sp. off. ARIETINA Roemer 



A small species of Exogyra, juvenile and young adult stages, was found 

 in the basal Weno at locality 611, near Fort Worth, Texas. The evolution 

 of the arietina group leaves large gaps to be filled in ; the group is known 

 from the Goodland limestone, upper third, and the Kiamitia marl (E. spp. 

 aff. plexa, ribbed and non-ribbed), from the Duck Creek limestone (E. 

 plexa) ; the Mainstreet limestone (E. arietina) and the Grayson marl (two 

 species aff. E. arietina). 



PECTEN INCONSPICUUS Cragin 



PI. 11, fig. 4 

 1895: Pecten inconspicuus Cragin, Colo. Coll. Stud. 5, 1894 (1895), p. 61. 



Cragin's description follows: 



"Shell small, thin, subcircular, a trifle higher than long, slightly trun- 

 cated anteriorly and posteriorly, right valve gently convex, its outer sur- 

 face smooth except for faint concentric striae and a few remote, subim- 

 bricate growth-lines; umbonal angle sharp at apex, nearly a right angle; 

 anterior ear (imperfect in the type) re-entrant below, as indicated by the 

 direction of the striae upon it, outline of posterior ear marking an obtuse 

 angle, its posterior margin rather more than one and a half times as long 

 as its dorsal. Left valve unknown. 



"MEASUREMENTS : Height 9.5, length 8.75, convexity of left valve 

 1 mm. 



